[T-Mobile LG V10 Q&A, Help & Troubleshooting] br0adband:
1) Get the LG Phone Info app on the Google Play Market and as long as that shows "OK" in the Original info (the first box after you click the Get Information button) then your device is an original and not something that's been modified on a firmware level.

2) If you have Lollipop or Marshmallow rooting is fairly easy by comparison to Nougat. If you have Nougat on it already things are basically a stop - there is no working root for Nougat at this moment IF the device has been upgraded to Nougat using T-Mobile's OTA direct from them. Once that's been installed there's no turning back and no working root at this point but some devs are working on it, no guarantees they'll ever be able to create one.

If the device has Lollipop or Marshmallow on it you can get it rooted. The best course of action is to go from Lollipop to Marshmallow (the last Marshmallow build is 20l and that's an "L" there, lowercase, not 1 or i/I) and then what you'll need to do is get TWRP on it (that step is critical) then you would flash this modified update.zip to get to Nougat build 30b on it. runningak3d modified that update.zip file so it does NOT overwrite the recovery partition and you get to keep TWRP installed for flashing purposes. If you use T-Mobile's official OTA update.zip you'll be stuck, not able to flash anything including TWRP, or get rooted, etc.

So, again, the process is get to Marshmallow 20l, then get TWRP installed - at that point root is not necessary just to get the modified 20b update.zip on it. Then use TWRP to flash that modified 20b update.zip at which point it'll be Nougat, and THEN you can flash SuperSU with TWRP and you end up with a V10 running Nougat and rooted, that's the only method at this point.

runningak3d said he (or she, sorry, I just don't know) would try to create another modified update.zip which is pre-rooted so when installed you've got root/SuperSU ready to go but it's barely a minute to install SuperSU manually after flashing that modified 20b update.zip so it's not really a big issue there.

3) There are no custom ROMs for the V10 at this point, no Lineage, no AOSP, nothing really. There are some modified stock ROMs iirc but nothing that's totally custom and we V10 owners are still hoping some dev will take some time and create an unofficial Lineage build for the V10 based on Nougat (or even Marshmallow, I don't really care which Android version it's based on just that it's Lineage through and through). It seems pretty screwy that nobody seems to care about the V10 enough to have created a custom ROM but that's how it goes sometimes. The V10 is like an LG G4 on steroids in some respects, basically the same hardware overall with some minor differences (the second screen, of course, but I don't even use that on mine so I don't care about it at all).

I just wanted Lineage because it's so lean and efficient compared to any stock ROM and of course the potential for having a custom kernel with more governor support and other aspects is the big draw for me so, the hope remains that someone out there will take some pity on us woeful V10 owners and drop a Lineage build someday. :)

As for apps, well, that's entirely up to you and what you use your V10 for, and since nobody knows that but you then it'll be up to you to decide what kinds of apps you're going to be looking for.

4) Over-and-underclocking requires a custom kernel that allows for such things, and the stock kernel that's available (I think there was one custom kernel but it's just a modified stock one with limited additional capabilities) simply doesn't allow for such alterations. The V10 is quite fast on its own natively so, I can't imagine why someone would need to overclock it - I can understand WHY someone would WANT to do it, of course, but as for an actual need to do it, nope.

As for underclocking, that would save battery and be what I'd call a need in some respects, but again there just doesn't seem to be any developer out there that gives a damn about the V10 sadly. I wish I had spent more time learning how to create custom ROMs over the years and trick out some kernels as well using the provided source from manufacturers of these smartphones but I never did.

5) There is no way to prevent the potential bootloop issue which affects the G3/G4/G5/G6 (I saw one report so it could be bogus for the G6) and also the V10/V20 (seen two reports for the V20) and the Nexus 5x because it's a hardware manufacturing defect related to how the Snapdragon SoCs are mounted on the motherboards. There's nothing that you can do about it and there's no way to know for sure if the V10 you have will develop problems because of it or not, all you can do is use it and be done with it and hope for the best. Again, there is no fix and there's no way to know or prevent it from happening so, no matter what so called "fix" you read about or see a video about, it's all BS and best avoided.

My recommendation: since you just got the V10, go to LG's website and register the V10 in your name (might have to create an account) and then say you bought it in March, April, or May of 2017 (just a few months ago) and that will give you warranty protection through at least mid-2018. If you do that and it does bootloop on you, LG will replace it through the warranty period. Don't register it and you're out of luck if it does bootloop on you.

Hope this helps...