As far as the boat, it is bigger than the launches that go to the resorts, and probably holds 30 or so people. There are bench seats on both sides, and we were sitting 3 to a bench, while some of the kids had 4. There was room in the back for wheelchairs and strollers to be stowed away, and they didn't have to fold them up.
The dessert reception had soft drinks, coffee, hot tea and bottled water, along with some pre-packaged snacks (which was better than the first time we did it, which was shortly after the GG stuff began. It was difficult for the kids to wrap things up in a napkin to take along on the boat). There were brownies, fudge, some granola/trail mix kind of bars, chocolate "coins", and a few more things that escape me at the moment. Capt. Hook and Mr. Smee spent a lot of time there with us, and posed for plenty of photos.
You also receive a special pin that you cannot buy unless you take the cruise, so I hear they are pretty collectable (we have about 6 of them, lol).
Once you board the boat, the pirate captain "Patch" leads sing a longs, and acknowledges any special occasions. You then get to watch the Electrical Water Pageant on Bay Lake, followed by getting in position for Wishes. The music is piped onto the boat, and they "park" so that you're looking right down Main St. to the castle. After Wishes, Patch plays Disney trivia with the kids on the way back to the Contemporary dock, giving away prizes for correct answers. Once you arrive at the dock, Peter Pan and Tink are there to pose for pics and sign autographs.
Hope that helps!