I'll see if I can chip in... I have a black v500
1. Ummm look for LG logo? Buy from reputable source. Not sure what you're looking for here
2. Some people have reported a blue line on the border of the screen. I've seen a few people who reported light bleed as well. (No issues at all with mine and many others around here)
3. Short answer: no. Not now. Someone has it in alpha version right now, but it cannot really be used... Only for testing at this point. There are a few AOSP ROMs such as CM, PA, AOKP and Mahdi ROM all running though.
4. The hardware is identical, but the app is bundled by LG so I believe that means you are looking for a third party solution... Someone would have to verify this one though.
Hope that helps
Sent from my LG-V500 using XDA Premium 4 mobile app