Definitely find out about rakeback before you make an account. If you do a Full tilt (among others) deposit, DO get rakeback. Google Rakeback for info on how to do this (I didnt and dont have it....) I agree with Ellie about not depositing all at once. You can do maybe 100 at one site, and see what games are for you (online a lot different than live, SnG is my game of choice, but a WAY different approach is needed compared to cash).
I cant suggest a site, but Stars, Full tilt are good, many others as well. Google
poker sites, Traffic, Best cash sites, etc and do the research before you deposit. A smaller deposit and a bit of sniffing around is probably a better way to start. You can always deposit again.
Good luck.