Since Mr Weasley was shocked that Harry was being tried by "the whole court," it seems that only delegations from the Wizengamot would be present at most trials. Only really serious crimes, like murder or use of the Unforgivable Curses, would seem to merit a full trial. Also, Mr Weasley seemed confused that it was "down in Old Courtroom Ten," so most trials probably don't take place there. (You've got courtrooms 1-9 to choose from, though!)
I would imagine that he would be tried by about five to ten of the Wizengamot, NOT in Courtroom Ten. As far as Magical Law Enforcement goes, you have pretty free rein, since Jo hasn't told much about it. He would probably be arrested by Magical Law Enforcement, sent to Azkaban (*eek-dementors*), and have to wait for trial, if it's anything like the Muggle world. I would think that wizards wouldn't have lawyers and such, though. With things like Veritaserum to force truth, that would be rather unnecessary.

Hope I helped!
schwartzy
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Formerly known as MrTibbles
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