Welcome back!
1) Sign in to each VT tournament. Once you have won credits, you're "in".
2) Nope - all tiers qualify. Only difference may (still) be that Amateurs and Hack do not earn credit winnings.
3) There are no handicaps here. Your average must be 80.0 or lower, with 10 Amateur rounds counting in.
4) Nope. Only one CC membership.
5) At least, from the distance, some tolerance against the feeling to be scammed seems necessary. IMHO, putting real money on the desk is better.
6) There's a search function over there =>
Use it for a plethora of detailled information.