I don't know the answer to your question about Camp Dolphin, but I suspect you get 2 free hours of child care only while the adults enjoy dinner. I think the idea is to discourage people from bringing young children into the more adult restaurants.
Each resort has its advantages. I prefer the Swan because most rooms have a sink inside the bathroom, plus another sink outside. The Dolphin's rooms have one sink outside the bathroom. The buses to the MK, AK, and DD pick-up and drop-off at the Swan before the Dolphin. The Swan is closer to the Boardwalk - for those who like to walk to Epcot or Hollywood Studios. The Swan is also half the size of the Dolphin, so it's easier to get around.
The Dolphin has a fabulous lobby that makes you say "WOW" the moment you see it.

The Dolphin also has the laundry room, game room, ice cream (Dolphin Fountain), and Picabu (24-hour buffeteria). My first 4 stays were at the Dolphin, and I didn't think anything could be better - until I stayed at the Swan!