There's been a lot of changes to the Fort Wilderness transportation. There are no more Chip & Dale, or Boone & Crockett buses.
Unless things have changed since I was last in the woods......
Since you're staying in the cabins, you will be on the Purple route. Outpost Purple will take you to the Front check-in area. You can get an Epcot, Animal Kingdom, and Downtown Disney bus there.
Settlement Purple will take you to Pioneer Hall. You can catch a boat to the Magic Kingdom, or you can catch a bus to the Disney-MGM Studios here, as well as a bus to Wilderness Lodge. Only after the MK closes, the bus will continue onto the TTC.
The internals runs on a fixed schedule, departing the Outpost and the Settlement every 10 minutes. (Unless they get held up and put behind schedule)