There are plenty of discussions in this forum on taking childern on cruises. You should not have a problem doing it, we just came back from a cruise on the Spirit and there were plenty of young childern. Camp Carnival will take him for as much of the day as you care to have him there. Babysitting is available for evenings after CC closes but it is an extra hourly fee. Some excursions have age limits and those are posted on the excursions area on the CCL website. I see no reason why he could not go on the stingray tour, but they may frighten him, you will have to be the judge of that. The stingray sandbar is not too deep for an adult to stand up on so you could hold him and stand doing it. You may want to bring a small child ski life perserver for him to wear though. The dinning rooms provide kids menus and don't seem to mind if you bring in children at all. But again, you need to be the judge on if you feal that he can handle being in the dinning room for the hour or so it takes to have the meal. You could always leave if he gets fussy and eat on the lido deck... or take him to Camp Carnival and pick him back up after dinner.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013