I'm trying to do my very first mod to my gtab. I've posted some questions already but have more before I proceed. I'm running bootloader 1.2-4349. Do need to set up nvflash before I attempt flashing to a different ROM? Is there a CWM that is specific for my bootloader? I've searched for these answers on the forums but was unable to find them. I found many posts about these subject but no one answred them directly. Any help is much appreciated.
NVFlash is never needed to flash a rom. It's a tool typically used to recover from a "softbrick." It CAN be used to flash a rom, but there are much safer alternatives. In fact, NVFlash is considered to BE the alternative to the regular methods.
starting with 4349, 1.2 bootlaoder, you can use the stock recovery to flash just about any of the 1.2 roms.
Which Rom are you interested in? The only roms that do not have a 1.2 equal are the gingerbread type roms. For instance, if you wanted Vegan 5.1.1, then Brilliant Corners is the 1.2 alternative. That's what I'm running. It's got to be one of, if not THEE, most complete rom available right now.
most 1.2 rom information is located at Slatedroid, not here.
I suggest that you check out the new website created by a user here (GoodIntentions). It's a "G-Tablet for Dummies" website. It contains a ton of useful information for beginners like yourself.
There IS a CWM that is specific to the 1.2 bootloader, but becuase the recovery on stock 1.2 has more options than the stock recovery used on 1.1 bootloader, it's not absolutely necessary. It's a good tool to have, but not necessary.
Your basic flashign technique for a 1.2 rom is as follows...download the .rar file the coincides with the rom you want. Unzip it to the root of your G-Tablet's memory. Restart the G-Tablet while holding down the volume up key. The tablet will boot into the stock recovery, and use the files you unzipped to flash the new rom. The rar file will contain to objects, a file called update.zip, and a recovery folder with a "command" file in it. What will happen when booting into recovery is that the tablet will first check to see if there is a recovery folder present. Think of this as a PC checking the floppy drive for a boot image before booting from the hard disk. If it sees the recovery folder, it will, by default, run the command file within it. The command file will unpack and install (flash) the rom image from the update.zip file.
With most of his roms, Roebeet has included the 1.2 CWM image in the package. It will not install automatically. There are threads available (on slatedroid) that contain instructions on how to activate the 1.2 CWM. There are various methods, if one doesn't work the first time.
If you are dead set on flashing a 1.1 rom, you'll first need to downgrade back to firmware 3588, which is a 1.1 bootloader firmware. Gojimi has posted instructions on XDA on how that is done.
So, your first step, is research the roms on XDA, Slatedroid, and other Android Tablet forums to find which one would best suit your needs.
As a beginner, I highly suggest that you steer away from the honeycomb roms, as they are still in alpha status and mainly used for testing and troubleshooting. In other words, they won't work perfectly, so to save yourself headaches, wait until your more comfortable with a more polished rom. ALL HC ROMS ARE 1.2 BOOTLOADER ROMS
The gingerbread roms are pretty stable, and from what I hear, pretty fast, but they lack a few things, namely full hardware acceleration. At the same time, if your heart is set on streaming netflix movies, then these might be the best choice for you. THE MOST POPULAR GB ROMS ARE 1.1 BOOTLOADER ROMS
The Froyo roms, while the most prehistoric are the most stable, most complete, and less "buggy" of all the roms. There are many varieties, based on various tablet user interfaces. FROYO ROMS CAN BE EITHER 1.1 OR 1.2 BOOTLOADER ROMS...BUT, the 1.2 branch has more of them, and there are 1.2 equalivents to just about all of them, so sticking with 1.2 for a Froyo rom is the best option because you'll still have the advanced stock recovery if you decide to stick with it.
That being said...why not mess around with the stock 4349 firmware to get a feel for the tablet a bit more? Check some things out. Get Titanium Backup and practice a bit with backup up apps and restoring them (you'll use this a LOT, especially if you rom jump trying to find the best one for you). Find out what you want the tablet to do, based on the stock firmware limitations. Some people are still using stock and not finding it too horrible. Spend a week with it, see what else you want it to do, and ask again when you know what you want out of your G-Tablet. And above all, ENJOY...you just entered a whole new world of personal computing...don't rush into anything and end up regretting your purchase.
P.S...I highly recommend you check out "G-Tablet for Dummies"
DarkHorse281 said:
I'm trying to do my very first mod to my gtab. I've posted some questions already but have more before I proceed. I'm running bootloader 1.2-4349. Do need to set up nvflash before I attempt flashing to a different ROM? Is there a CWM that is specific for my bootloader? I've searched for these answers on the forums but was unable to find them. I found many posts about these subject but no one answred them directly. Any help is much appreciated.
Click to expand...
Click to collapse
Check out my website written for beginners. It will explain everything you need to know.
http://viewsonic-gtablet-for-dummies.webs.com/
Added by edit.
Make sure you read my page on flashing a rom.
http://viewsonic-gtablet-for-dummies.webs.com/rom.htm
Also, check out my page on CWM.
http://viewsonic-gtablet-for-dummies.webs.com/clockworkmod.htm
Much appreciated...awesome!
You guys are both awesome and a credit to the anroid community. I can't tell you how much I appreciate you help. I didn't go into much depth on this thread because I had already written one earlier in the day that shared my background and future intentions for my gtab. I didn't want to sound repetative plus I realize people don't care to read a novel in these forums. So I figured short and sweet I might get a better response, and I was right. Anyway, I hear what you're saying about messing around with the stock firmware TJ. The truth is I've had the tablet now for 3 weeks and I've played with it constantly. I have to say it's not as bad as I thought it would be but it lacks so many things that I've come to love about my Samsung Galaxy Indulge. Many people make fun of or pick on Metropcs and make fun of them as a company, but I have to say here in Florida they're great. I love my phone even though its not the top of the line galaxy phone. And their 4g service is fast in my neck of the woods. Having had such a great experience with that android device, I would really like to make something awesome out of my gtab. I want to use the 4g on my phone to connect to the internet and turn this tablet into a completely mobile multimedia device (Xvid, Avi, Mp3, Netflix, Hulu). I would also like to get the gps software put on it so that I can put my google maps app from my phone on it. Once I am be to get the phone rooted and the wifi or usb tethering up I can use it for navigation as well. I also miss the Android Market. I would love to get that back up and running on my tablet so that I can download some of the apps that I'm familiar with. I really like the dolphin browser on my Indulge and would love to have it on my tablet. I had it for a while on the gtab but had to do a factory reset because of something my kids did and now that I'm back to having nothing on my tablet I thought now would be a good time to try a different ROM. Besides it seemed a little glitchy anyway. Sorry about the novel guys, but now that you know a bit about me and what I want to use my tab for, which ROM do you think will suit my needs? Do you still think that Brilliant Corners is going to cover what I'm wanting out of my gtab? I'm going to check out GoodIntentions' web site and maybe I will get a clue. Thanks for your help guys. I hope to hear back soon.
P.S. One additional question. What's up with the bluetooth pairing? I can't get this thing to pair with any phones. I've tried mine and my gf's and it absolutely will not work.
Related
...a pain in the ass for the Fascinate. The gf has one of these phones, and after seeing what I've done with my G2, she wants me to root and flash a nice rom.
Problem 1 (not so small): we both use macs at home.
Problem 2 (huge): after reading through the development forum - it doesn't look that easy to root, nor flash a decent rom on the Fascinate!
not only do some roms require you to have a specific kernel flashed to use them. Some roms require that you don't use the latest CWM. Also, none of roms seem to be using Gingerbread AOSP completely. They seem to be pieced together with Froyo.
Believe you me, I am not a dev in the slightest. Therefore, I am looking for a safe way to root and flash a decent rom to her phone. If there isn't, then I'll just let her run stock.
Is this easier than I'm seeing it?
enserio said:
...a pain in the ass for the Fascinate. The gf has one of these phones, and after seeing what I've done with my G2, she wants me to root and flash a nice rom.
Problem 1 (not so small): we both use macs at home.
Problem 2 (huge): after reading through the development forum - it doesn't look that easy to root, nor flash a decent rom on the Fascinate!
not only do some roms require you to have a specific kernel flashed to use them. Some roms require that you don't use the latest CWM. Also, none of roms seem to be using Gingerbread AOSP completely. They seem to be pieced together with Froyo.
Believe you me, I am not a dev in the slightest. Therefore, I am looking for a safe way to root and flash a decent rom to her phone. If there isn't, then I'll just let her run stock.
Is this easier than I'm seeing it?
Click to expand...
Click to collapse
Honestly, it is not that difficult. Just takes some getting used to. Obviously you have done a bit of reading, I know it seems daunting, but I promise, once you have it down it is nothing. The kernels...Most ROMS are kernel switchable, within reason. MOST of our ROMS require the RED CWM, which honestly is not a big deal, the orange is just too glitchy. And as far as the ROM's being pieced together with Froyo...Well, I am no dev either, but yes, I believe most of the ROMS are a Frankenstein of sorts, but we don't even have a Froyo source to work with yet. So the dev's, in my opinion, have done an AMAZING job. In terms of flashing on a Mac, I am not sure if Odin works on a Mac, Heimdall does though I believe. Rooting is extremely simple, it is only the flashing the right CWM, modem, etc. that may confuse you. Honestly, if you just keep reading the right things, you'll see it is pretty simple. I recommend Adrynalyne's Super Clean 2.9, and Big Loof's Steel Blue theme, with the EB16 kernel (Also Adrynalyne's).
http://forum.xda-developers.com/showthread.php?t=948722
This thread has a good walkthrough, I'd follow it through Post #5... using Superclean. It's an incredibly performing full Froyo rom. Remember that Froyo is not officially out on this phone, she's running Eclair right now. Gingerbread is a ways off (though punk kaos is making great progress).
Before EB01, rooting for me was just clicking a single button.
I never had to root again since flashing EB01. For flashing itself, its just download, reboot to recovery, and flash. Not sure how its a pain in the as as it doesnt even take a minute or so.
I did end up installing 3.XX CWM from ROM manager, but I only reboot into orange CWM if i reboot using ROM manager. If I dont, I end up rebooting to red CWM.
Thanks for the responses. Put a few things in perspective. I totally forgot that she is still running Eclair and Froyo isn't officially out for these phones. My mistake, and now that makes complete sense to me why most of the roms are froyo based or patched. Another thing that made me hesitant is that Odin doesn't run on mac, and I would have anything to save the phone (unless I use one of the pcs at work) if something goes awry. I will read up on Heimdall and see if I can use that.
My apologies if I sounded bothered or uptight about the situation, thanks for the well-mannered responses to my mini-rant. Of to read up a bit more, starting with the link postd and Heimdall.
Found a quick guide for rooting the Fascinate with a Mac. Now my issue is...switching to EB01 without Odin because SuperClean needs it, correct?
Folks...
I've been using ClockworkMod for a while on my HTC Incredible and today I received my Woot table.
I installed ClockworkMod on the tablet and did a backup of my "stock" image (I applied the 3588 update).
From reading these ROM threads, it looks like there's some differences in how I am used to interacting with Clockwork and some of these warnings sound pretty ****ing dire...
If I install a ROM, isn't going back to my previous backup a matter of formatting and restoring? It sounds like some of these ROMs interfere with Clockwork in such a way that could result in a bricked device. I've been wiping and restoring on my Incredible for almost a year now and I've never heard of a ROM dicking with Clockwork before...
What's the difference or am I making a mountain of a molehill here?
There is a very specific version of CW that bekkit put together for the G=Tab. The problem isn't the rom messing with CW, it usually is Rom Manager that will mess with it. Rom Manager usually will want updated, especially with CM installs.
I have had to nvflash the tablet in the past after upgrading CW via rom manager.
The other issue that is common, and I have had happen to my beloved Dinc, is having to repartition the storage. The groundwork for the Dinc was much, much more stable than the default tapNtap that is released with the tablet.
Something some people may also miss is the kernel for GB is much different than the kernel with froyo.
Rest assure, bricking this thing seems to be an accomplishment and almost impossible. Trust me, I have given my best effort to do so. With nvflash or adb almost any tablet can be recovered.
One last thing to look out for, how internal storage is handled. Some roms use internal as emmc (like the Dinc), while others mount as sdcard. CW doesn't handle this switch gracefully. You can mount usb storage in advanced menu and move the recovery files over if needed.
While dharr18 is mostly correct there are a few ROMs floating around out there that will have trouble with clockworkmod. TwoTapsX and TnT Lite 5.0 (both currently held from distribution by the developer) are based on a UAT build (3991) that require using the stock recovery and bootloader from build 3588+ to install correctly. There is some speculation that this may be the standard going forward.
Thanks KJ, I forgot about those two as I have not loaded them to date.
dharr18 said:
The problem isn't the rom messing with CW, it usually is Rom Manager that will mess with it. Rom Manager usually will want updated, especially with CM installs.
.
Click to expand...
Click to collapse
Yeah, I fell into that trap... really FUBAR'ed my tab until i had to nvflash a full recovery.
dharr18 said:
Thanks KJ, I forgot about those two as I have not loaded them to date.
Click to expand...
Click to collapse
You're welcome. I run TTX regularly (well... in between my attempts to find creative new ways to brick this thing...).
Deacon,
The truth is there ARE some dire consequences. Bricking a G-Tablet is extremely hard,
but you can lose data. If something breaks on your tab and your have loaded a ROM
you do not have a warranty. There are risks involved.
And in my opinion a lot of people try to do too much too fast and too often wind up
in dire straights.
There are stickies on most of the recovery/problematic stuff. Good to read them first.
Rev
the problem isn't with the ROM
I follow roebeet and the tnt lite ROM - VS is updating their boot loader from 1.1 to 1.2 in some of their OTA updates. Mostly the 3588 and the 3991. If you are playing with those or it came installed then it can be a bit of a hassle depending on what ROM you are playing with. I updated my gtab to 3991 and was able to nvflash it back to 3588 and install vegan5.1 and tnt lite up to 4.2 without any issues. Just be sure to read up and be able to complete an nvflash if it gets ugly on you. I really recommend learning a little linux - nvflash is a breeze in there.
So, firstly, big thanks to the devs here. Gt ADB up and running and started the seemingly easy process f flashing ClockworkMod.
However, I'm not getting to ClockworkMod after resetting. If I try booting into recovery, it stays on the birdie splash screen with "Recvery key detected" and "Booting recovery kernel image" in the upper left.
Not finding any options for alternate recoveries or a fix for this.
I bought it used and the original owner had done some stuff to it so perhaps I was not meant to flash Clockwork from here.
Tap UI version is TnT Lite v5.0.0
Kernel version is 2.6.32.9-00001-g0e0c333-dirty
The standard ClockworkMod does not work properly with TnTLite 5.0. You need the one that was specifically compiled for that ROM.
Go here: http://forum.xda-developers.com/showthread.php?t=998663
and scroll down to the bottom of the first post for a link to the compatible version.
I thought that might be the case although I was told I could flash CLockworkmod once 5.0 was on there.
I'm normally a bit better at figuring all this out but starting in the middle of someone else's work has me at an awkward spot.
I've been searching with little luck. Any chance of pointing me in the right direction?
What about a complete factory reset? Would it be advised at this point?
I editted my previous post with a link to TwoTapsX (Experimental) which is identical to TnTLite 5.0. That should get you going but I'm not sure how much damage might be done at this point. I would try just installing the compatible version of CWM and see if that works. If not, we can look at other recovery options.
Just in case... Are you familiar with nvflash? http://forum.xda-developers.com/showthread.php?t=861950
Just started reading about nvFlash and paused to ask the questions before hacking away blindly at my new toy.
I really appreciate you pointing me in the right direction.
I enjoyed the ROM he put on here but, like the poster under me, my data suddenly got deleted and I like to try various ROMs anyway so I set to work.
I rarely leave my tablet running the same ROM for more than 12 hours ;-)
Be aware that switching away from this particular one can be a bit tricky. I find that doing a cache and data wipe before starting helps to boost the success rate. I also try to down grade to stock 1.1-3588 before loading anything else. If that fails it usually results in nvflashing back to factory stock.
Ack! Okay, in what is sure to be yet another Windows 7 issue, I'm having trouble running the .bat file for nvflash.
Are you sure it is the Bat file. Windoz7 64 need a different driver for NVFLASH.
The drivers I used appeared to work. I will try again.
Damn, I'm sorry. I swear I'm usually better at figuring all this crap out for myself. Once I'm back to stock, I can work from the beginning. This is like being dropped into the middle of a David Lynch flick with zero context.
When I run the batch command, it says that nvflash.exe is not recognized as an internal or external command. Weird.
Did you extract both archives to the same directory?
I sure did. I did take it to mean the gtab folder should remain intact within the nvflash folder instead of mixing the contents altogether in one folder. Right?
Everything else seems to be in order.
Putting any recovery zip on the sdcard produces the same results. Thankfully, everything seems to be working aside from the recovery. Maddening!
I think they need to be intermixed. Would have to check the original thread or look at the .bat and .cfg files to be sure... but if I recall properly they do.
All the files from both zips should be in the same folder, otherwise the batch file can't find nvflash and you get that error.
Good luck!
Wow. If that's what it was they need to put a dunce cap on my avi. Thanks for all the help. I shoulda had the guy put it to stock so I could start from scratch.
I'll try that when I get home.
Thanks again!
Sent from my HTC Vision using XDA Premium App
Sleef,
You are in a world of hurt -- and I say that not making any negative comment
toward the advice you already have been given.
TnT Lite 5.0.0 (which is now TwoTapsx) is a second generation ROM Roebeet did
based on the UAT 3991 update posted by VS in a kind of test mode.
The second generation ROM is not compatible in many respects with the original ROMS
up to 3588 -- some of the internals that normally are changed in an update have been modified.
So, as you have been properly warned by others, you cannot run stock CWM. You
also have to be careful downgrading to stock before moving to stock or another ROM.
To get out of 5.0.0 you need to:
1. Read Roebeet's TwoTapsX thread so you know what you are working with:
http://forum.xda-developers.com/showthread.php?t=998663
2. You need to NVFlash back down to stock. Normally we'd tell you to follow
the thread:
http://forum.xda-developers.com/showthread.php?t=861950
Since you already have been working with this, I'd step-by-step make
sure of your setup and that it is right.
My best suggestion would be for you to set up and follow the NVFlash thread above
exactly and see if you can get a good flash. If you do, it will take you down to what
we call bekit 1105, which is stock version 2638. If you get there and boot successfully,
then when you turn on wifi it will soon update you to OTA 3588. Then
you can carefully pretty much do what you want.
If you don't get a successful flash (because the tab has had so many different,
difficult to handle things on it), then all of us will have to help you find a successful
path.
Good luck,
Rev
P. S. -- What the other guys have been telling you is good -- I've just tried to
put it in perspective so you'd understand where you're at and be organized in
your approach.
Quick clarification... I think Rev meant to say "Is NOW TwoTapsX" rather than not which is why that thread is referenced later. The name change was necessary to differentiate the two development paths.
Thanks for popping in Rev. I've been meaning to pop in but I've been... practicing my recovery methods... don't ask...
Yep.
Fumblefingers strikes again. Thanks.
Rev
OK so it started with having a well balanced stock rooted 4.0.1
the main reason i root is for tethering
i had a carrier update that i was hoping was 4.1 cuz i am dying for google now
ran that but got stuck in the boot (as in not a boot loop but just infinite boot)
i would simply like to have my phone back on a stock rooted ROM* preferably ICS
i attempted "solutions" i found on here for using odin to "plop" a stock rooted ROM* on there but it turned out to be Gingerbread -_-
so i am currently dealing with that and what appears to be a stock Bootloader*
*i barely understand all these terms so please let me know i love to learn and i just cant wrap my head around all of it but any tips would be great. as far as i understand the boot loader is like the boot menu on a computer in the bios and is accessed when holding down all three hard buttons and gives you the selection menu, and the ROM is like the OS, and i think flashing is whenever you use odin to install the ROM instead of the boot loader for some reason.
I apologise for the noobieness but this is like the only way i learn...from direct Q&A :/
thank you in advanced
First off, download:
UCLE5 ICS- This is the stock AT&T GS2 ICS and is already rooted.
Fire up Odin, and:
Code:
Put UCLE5_Stock_Rooted.tar in the PDA slot in Odin.
Reboot your phone.
Oh and, a ROM is sort of a firmware that runs atop a kernel. Usually ROMs and kernels are put in ZIP files for flashing via ClockworkMod Recovery, but in specific cases (such as with Samsung), you can flash them via Odin or Heimdall in .tar formats.
Basically an Android phone needs both a ROM and kernel in order to run. From my very limited knowledge, a kernel is what controls overclocking and other processor related tasks. It also can help define the keylayouts for this particular device. It also contains the system recovery. A ROM holds all the system framework files that arguably makes the phone what it is to the average user. There are many ROMs that are available, such as Touchwiz (Stock/Modded Samsung), AOSP (Stock/Modded Android), Miui (Based off of either Samsung or AOSP, sort of it's own thing).
EDIT: Also, don't be sorry! Feel free to ask questions (as long as you've searched already), and remember that everyone starts somewhere.
We understand that you're new but please attempt to search your problem. Also, 4.0.1 does not and has never existed for our device so I don't know where you got that. Everything else though is easily found on Google, I don't buy that "I need spoonfeeding" line for a second.
Sent from my Zanpakuto using Getsuga Tensho!
PM me and I can give you further instructions if you still can't figure it out.
Hey thanks for your response!
I haven't had the time to try it out just yet (super busy lately) but as soon as i get the chance i will leave a reply as to how it goes.
Also thanks for the explanation. That really helps. I have always wanted to get more into the android field to learn more about the devices i'm using every day.
Ps: The reason for the apologetic sorry is to stand as a polite understanding tone from people who frequent the forums and discourage new posts while assuming no research has been done. i have searched for a good two hours but finding something relevant enough that i would be comfortable progressing through is very difficult and as i mentioned earlier i do learn better from direct Q&A. Thank you for understanding.
~Killubear
estabien said:
First off, download:
UCLE5 ICS- This is the stock AT&T GS2 ICS and is already rooted.
Fire up Odin, and:
Code:
Put UCLE5_Stock_Rooted.tar in the PDA slot in Odin.
Reboot your phone.
Oh and, a ROM is sort of a firmware that runs atop a kernel. Usually ROMs and kernels are put in ZIP files for flashing via ClockworkMod Recovery, but in specific cases (such as with Samsung), you can flash them via Odin or Heimdall in .tar formats.
Basically an Android phone needs both a ROM and kernel in order to run. From my very limited knowledge, a kernel is what controls overclocking and other processor related tasks. It also can help define the keylayouts for this particular device. It also contains the system recovery. A ROM holds all the system framework files that arguably makes the phone what it is to the average user. There are many ROMs that are available, such as Touchwiz (Stock/Modded Samsung), AOSP (Stock/Modded Android), Miui (Based off of either Samsung or AOSP, sort of it's own thing).
EDIT: Also, don't be sorry! Feel free to ask questions (as long as you've searched already), and remember that everyone starts somewhere.
Click to expand...
Click to collapse
I'm trying really hard to do this without being dopey. I want to get my Galaxy Tab 10.1 P7510 to slim down and speed up, so I want to root and apply a new ROM. This much I'm pretty sure of. I understand that I need to replace the recovery code, which will allow me to replace the stock ROM with a modded ROM. (How am I doing?). I think I need Odin running on my PC to load the new recovery. I understand booting into recovery mode (I think). I've read about putting the new ROM on my device and rebooting into it. I believe I then need to install google apps to get some of the basic stuff (like Play store) back on the device. I assume that is because they are not part of the modded ROMs? But... how the heck does one decide WHICH recovery, WHICH ROM, WHICH gapps and the right versions of each? I'm going around and around. I'm willing to do the research, but I'm not even clear on the high-level process and steps, let alone the details, finer points. I'm a retired app developer (client server, Oracle, Powerbuilder) so I have some idea of what I'm doing. Just some. Thanks in advance if anyone cares to help.
jberthoty said:
I'm trying really hard to do this without being dopey. I want to get my Galaxy Tab 10.1 P7510 to slim down and speed up, so I want to root and apply a new ROM. This much I'm pretty sure of. I understand that I need to replace the recovery code, which will allow me to replace the stock ROM with a modded ROM. (How am I doing?). I think I need Odin running on my PC to load the new recovery. I understand booting into recovery mode (I think). I've read about putting the new ROM on my device and rebooting into it. I believe I then need to install google apps to get some of the basic stuff (like Play store) back on the device. I assume that is because they are not part of the modded ROMs? But... how the heck does one decide WHICH recovery, WHICH ROM, WHICH gapps and the right versions of each? I'm going around and around. I'm willing to do the research, but I'm not even clear on the high-level process and steps, let alone the details, finer points. I'm a retired app developer (client server, Oracle, Powerbuilder) so I have some idea of what I'm doing. Just some. Thanks in advance if anyone cares to help.
Click to expand...
Click to collapse
A custom ROM can be installed via custom recovery or Odin, so you don't really need a custom recovery before installing it, however it is higly advised.
To say it all, you don't even need root to flash a custom recovery. Some custom recovery like CM also come already rooted.
It is because they are not part of the custom ROM, since including gapps source code would take up more space and some other issues. Regarding the fact about which recovery and ROM to choose... the fact that there is a lot of them doesn't mean that they are very different. Some are based on the source code of another and just add little features that one must be looking for in order to be interested. Generally, TWRP and CWM are the ones most documented. With a simple google comparision research you should be able to decide. Custom ROMs are also based on two vastly documentet projrcts: CM and AOSP. Start with the regular ones, try them both, stock with one if you don't need anything else or start looking around among the forks.
However, I started using custom ROMs with an objective: build source code. For this scope, I decided to use CM for it's huge documentation, since I was looking for a kernel that did one particolar thing, but there wasn't one so I did it on my own. Just to say, I don't know how it feels like to be in decisive about what ROM to pick up.
Ciuffy's SM-G900F CM 12.1 spirit hath marked this way.