Welcome to the board - you're in for a treat.
1. For me, it depends on how well I'm playing. If I'm playing sharp, then I automatically expect to place in each SnG. I can't say that this always happens, but I do really well, especially at the $10, $20 buyins. There's a lot on RGP about this question, and for a better answer, I'd say do a search on Google or RecPoker.com. As far as "sample size" I think 50-100 would be sufficient at each buy-in limit. You should get a good analysis of how you're playing - and, more importantly, whether or not you should continue to play them!
2. I said it before and I'll say it again, Party is the best for SnG action. Wide selection of limits and games, and it's the fishiest site in the poker world. I'll save you my affiliate link. Just go sign up.
__________________
|