I'll answer your questions in the order you asked them but if you need follow up, please be sure and do so in this thread.
What happens if he doesn't show up? They are talking about probation, and stuff...??
Usually they will issue a warrant for him. Many times in juvenile
cases they start informally requesting that you show up for a hearing but if you don't they then issue a warrant, file formal charges, etc.
What are my options, or what can they do?
What are my options is a pretty general question, but I'm going to try and provide as detailed an answer as I can.
Your options are really three. 1) Don't show up and see if they do anything, 2) show up without a lawyer and see what happens, and 3) hire a lawyer and let them handle it. Of the options, hiring a lawyer is the best way to address the issue since it is likely to result in the lease
amount of consequences (possibly none) for your son although it will cost you to hire the lawyer of course.
What likely happened is that the other kids somehow implicated your son although it certainly could have been unintentional and the result of a bad set of questions by the officer such as "who was here" instead of "did anyone else do this with you".