When you get to the port, they will give you a welcome aboard navigator (It's basically a list of everything that's going on. You get one each day for adults, and one for the entire cruise for the kids based on their age group). In the navigator, it will tell you when and wear you can register the kids in the club. Usually, there's a time in the early afternoon to register in the actual lab, and a time around dinner to register in the hallway. The programs don't usually open until early evening the sail away day, so you can't leave him immediately.
As far as eating, they offer lunch and dinner with the kids programs (only at a specific time, so if you want him to eat there, be sure he's there then), or he can eat with you in the dining rooms, or there are many fast food options or room service available. All are included in the cruise price.
While you're on the ship, you will have a pager. The counselors can page you. At 10, you need to decide if you'll let him sign himself out (your choice). If you decide to let him sign out, you can ask that they page you when he does. You leave the pager at the end of the cruise.
And yes, he'll have fun. I suggest you check out the kids navigators for his age group on
www.castawayclub.com