LG L Bello D331: Flashing a different region's official ROM

Hello everyone. I'm planning to flash an official Lollipop ROM on my LG L Bello D331, and I have some questions before I proceed.

My current ROM details:

Model: D331
Android: 4.4.2
Version: V10f
Region: HUN
Link: http://lg-phone-firmware.com/index.php?id_mod=54
File: D33110f_00.kdz
Size: 804 MB

New ROM details:

Model: D331
Android: 5.0.2
Version: V20c
Region: CIS
Link: http://lg-phone-firmware.com/index.php?id_mod=54
File: D33120c_00.kdz
Size: 899 MB

Questions:

1. I'm currently on build V10f_EUR_XX. Will it change to V20c_CIS_XX, or simply update to V20c_EUR_XX? If the region changes from EUR to CIS, what will exactly be changed?

2. Since LG delivers their updates via IMEI check (regardless of the region), will I still be able to receive official OTA updates?

3. New ROM is provided for Russian region, and thus includes the Russian language. My current ROM also includes Russian, and almost every other European language. Does that mean I will have all European languages on the new ROM too?

4. Finally, and MOST important: Some early adopters flashed D335 Lollipop on their D331 devices, and now they can't flash back D331 ROMs because their D331 somehow "became" D335. Since I'm flashing a D331 ROM on a D331 device, will I be able to downgrade if neccessary - or I will be stuck on Lollipop too? Does it matter if my current ROM is rooted? Also, if the region changes to CIS, will it revert back to EUR?

Since Lollipop was released for D331 in Mexico (Telcel carrier), Turkey (Avea carrier) and CIS (unbranded Russian region), is there any chance other countries will receive it soon? I mean, D331 hardware is EXACTLY the same in all regions.

Thanks in advance!