First, I just want to say that I "highly" recommend that you finish high school first. You are young but in time you will come to realize that education is very important, even if you disagree now, or if you don't like it too much (been there personally)

And to go back and finish it later on will be even harder. So I strongly recommend that you graduate high school first and then sign up for the military. But that's just my opinion.
Second, regarding the trial, I think that you should resolve that first. I was asked during the interview (and you might be too) whether I owed anything to the justice system, ie whether I was selected as a witness, or whether I was waiting for a trial, or if I was on probation. So that leads me to believe that one should deal with any solved issues with the justice system first, and then proceed with the application. Of course, I am drawing this conclusion from my experience and I might be wrong.
So really, the best advice is to talk to your local recruiter, they know best and they will be able to answer all your questions.