[G2 Q&A, Help & Troubleshooting] Sunandroid:
I'm on SlimKat. If you have Questions about it PM me. ;)

In my opinion, its running better than every other ROM. And batterylife is at least as great as on stock. I wouldn't say, that Stock ROMs are the smoothest/best ROMs at all. This statement can only be made by someone who hasn't tested different ROMs. ;)

Possible, yes. Another possibility would be that Samsung has designed like this and LG made it the same. Fact is it is not the best solution at all...

Do you mean the launcher? I don't think so. For mit hardly every feature had it's own APK. But I don't really know how it's about this feature...

NANDROID Backups are done in the Recovery. If you install a completely new ROM and not just a update (like you described on CM below) a clean install is highly recommended. Wipe everything except internal storage (SD Card) then Flash the ROM. All your apps and data will be deleted.

Just good to know: The name Nandroid originally came from the CWM Recovery (in my opinion pretty outdated now). But a Backup (and most people call it Nandroid even if for me and some others it's not really a Nandroid, but everyone knows what you want to say) in TWRP can not be restored with CWM and the other way around it doesn't work as well.

You won't have to disable anything. Once you installed another ROM, there will be no OTA Updates from LG, but maybe from your ROM dev for your ROM. But in some ROMs is not OTA functionality built in (not like on CM where you get OTA Updates).

Sorry for calling that a dumb question. But a new ROM is basically everything new. All data are gone (except SD card). Only on updates like those from CM or LG where the same Sources (Android 4.X for example), system Apps, etc. Are used it's possible to keep your data. If you are using NOVA Launcher (or any other Launcher that has the option to backup your launcher settings) and you plan to use it on the new ROM as well, you can backup those things and restore as soon as you installed the launcher on the new ROM.

Well: Your nandroid is gonna be saved on the SD card and then it will be deleted --> How do you want to restore anything out of it?! ;)

Your SD card is the only thing what you never have to wipe before installing a new ROM. ;)

As already said, hardly every ROM has built in an option, that shows you if a new update is available and where to download it and how to flash or it has exact the same functionality like CM or Stock.

Something about different flash methods. Just that you realize what CM (and every other manufacturer does). They do basically a dirty flash. Dirty flash means, that you do not wipe anything like apps and data and just kind of overwrite parts of the system (and maybe boot) partition. So all your settings and data and so on are kept.

If you switch to another ROM (CM to Mahdi or so) or the base of the ROM (from CM10 (Base: Android 4.1+) --> CM11 (Base: Android 4.4+)) a clean flash is highly recommended. A clean flash means wiping everything (including apps and data) and setting up everything new. It is really important because ROMs create data to run better and smoother. And some ROMs (Android Versions as well) do that different than others. So if you wipe, the system creates those data new. If you do not it tries to use old data that is already there but maybe incompatible with the ROM. So you simply avoid bugs by clean flashing. ;)

After reading my whole post, it should be possible for you to answer the last question on your own. ;)

---------- Post added at 03:08 PM ---------- Previous post was at 03:02 PM ----------

Try out a AOSP ROM. Maybe it's an issue with LG's sources that persists in cloudys ROM. I don't know, but it's possible. I have never faced such a problem on my D802. Appears this issue only on ZVC/ZVD?! It might be possible^^ Maybe you can try to downgrade your Play Services/Store and try again...