Anderson, welcome to my neck of the woods. You will enjoy it and will find some good baseball. Yes the three that strike 3 are very good and you can find their websites pretty easy. I know the pirates and gamers will have two teams at each age group, and both have tryout info on their site. The prospects have a few teams that you can see on their site. I dont know much about them. Then there are other "club" type teams.
St Louis Sting
St Louis Recruits
Warriors
Cougars
Legion is the same as everywhere else. SLABA is a lot like legion but there are only 10 groups of teams, based on what high school you would attend if you attended a public school.
http://www.slaba.net/default.htmIf you would know where you were attending school in the fall, you could figure out what team you would play for.
I know a few high schools have summer programs. Some of the private schools do, so if you are going to go that route in the fall, you could find out who the coach is and contact him.
If you need anything else, just holler.