Full Tilt now has the toughest players. I'll mostly play the Sunday Tourneys and some NL400 or NL600 on there, no higher. I used to play NL2000 on FT but it just got tougher and tougher.
Stars is good up to NL5000, where it gets very very tough and agro. I play NL1000 on stars mostly and they DEFINITELY have the best management.
I'm also playing on UB recently, but there's not much action above NL1000.
To get small amounts of money on, you'll need to buy a Green Dot Mastercard. It's a prepaid card. You can load up to $2000 at a time. If you get a Platinum card, you can load more but you need to pass a screening process.
Money orders or checks work, too, but can take a while. I've been playing for 4 years and have several friends who keep hundreds of thousands online (bad idea IMO) so I just hand them cash and they transfer for me.
Good luck, see ya at the tables.