1) Yes, public gallery as above.
2) Don't think so. I don't thinks ou can interrupt a trial. Gotta go through the cops. Maybe if, when you go, you talk to the usher, you can get some advice.
3) depends on the sentence, and bail.
When I was a juror the defendant could go home, I assume, when the hearing was adjourned. If the sentence is suspended they don't go to prison until they do something else.
4) Maybe you can ring the court, I dunno. Presumably there's a list on the day. If you're involved they might tell you in advance. Ring the court.