Hi,
Cost is $11 per person per round trip, don't think there is a discount for children. As far as I know they run at 9:20 am and 12:00 pm from the Clubhouse and return at 5:00 pm, 8:00 pm, or 9:30 pm. Depending on how many people you have, may be cheaper to get a taxi. The company that runs the shuttles is Maingate Taxi - 407-870-5553 so you can also call close to your time to verify cost and schedule.
There is also Goodtime Taxis - 407-847-8777 - and I believe round trip to Disney (up to 7 people) is around $50, but also call to verify, as things are always changing. Time there would be as scheduled and doorstep to doorstep.
Hope that helps.
Sandy