"This is Vera. What do you know about her?"
Translation:Это Вера. Что ты о ней знаешь?
"Что о ней вы знаете" sounds unnatural. The better options are: Что вы о ней знаете? or Что вы знаете о ней?
Yes, you can use «вы» instead of «ты» (and then change «знаешь» to «знаете»).
However, it really sounds better if you put «о ней» before «знаете». Unfortunately, I can't explain why, it just sounds better.
I have a question! Знаешь is the "you" - form of the word "know", right? Why do I need the ты? Just curious!
As you would say "you know", Russians say ты знаешь. As simple as that :)
"вот" means "here is" when handing or pointing something out to someone. One situation I think it would be used is when someone comes to your office looking for Vera, and when she arrives to meet them you say "вот Вера" (non native speaker disclaimer)
Please see the guide by olimo: https://www.duolingo.com/comment/11536858
If you say Эта Вера, you mean "This Vera". Это Вера = "It is Vera". Это окно can either be "This window" or "It is a window".