1. Does your son have roommates lined up that he wants to live with, if so I would get there no later than 7 am to get in line with them. Or if he is set on wanting a certain apartment complex and bedroom setup? If he doesn't care it doesn't really matter what time he gets there. The upside to being in the first half of the line is obviously more apartment options available and being in the first group to go to Casting.
2. Parents hang out in a tent with tables and chairs while they do the check in process, then you can go with them to their apartment and help them get set up. My Roommates parents unpacked her stuff while she was at Casting. Casting can take hours and there is no where for parents to wait other than the apartment or going to lunch or something.