There are five bus stops at OKW with the Hospitality House being the last stop. We have never had any problems with getting the bus to the parks. You probably want to ask for a water view or close to pool. The Old Turtle Pond Pool is pretty nice and has a food area that is open seasonally.
Olivia's has great breakfast, very good lunch and pretty good dinners. I love all their sandwiches.
The boat to DD stops running about 9:40PM. It's not very big, only holds about 11 people on a run.
If you don't need a handicapped room, make sure you list that as one of your first requests; also non-smoking if that is important. We have usually gotten our requests as long as we make them general - non-smoking, water view, etc.
You 6 yr old will have a great time. They have all sorts of activities at the Community Hall, games, crafts, etc. No slide at the pools, but they are all nice pools.
Don't forget that you have access to free washer and dryer near the pool. You just have to share it with all the other studio people. When we stay in a studio, I get up early (6 or so) and get a load or two done before the rest of the family gets up.
You can also rent the surrey bikes at OKW and they are cheaper and much easier to ride that BW since you don't have all the hills.