Brenda:
Our family stays at
Fort Wilderness at least once year if not more. Without a doubt, you'll want to take Disney transportation via boat to the Magic Kingdom. Keep in mind that you cannot drive your car to the marina from the cabins as there is no parking, so you'll want to catch one of the fort's internal buses to the Settlement and then walk over to the marina.
As for the other parks, if you have a car, I recommend driving to all three parks: Animal Kingdom, Disney's Hollywood Studios, and Epcot. First, you won't have to walk, rent a golf cart, or take an internal bus to the Outpost bus stop nor wait for a bus to one of these parks. In my experience, this can save you up to 45 minutes one way and parking at the theme parks is free. If you don't bring your car, consider renting one. The cost to rent a golf cart for the length of your stay at the fort to use to drive to the marina and to the Outpost can actually be more than renting an economy car at the airport.
Wishing y'all a magical vacation!
Whitney