Hi-- we'll be down there in December, too!
To get from ASMu to Fort Wilderness: The bus system within FW leaves a lot to be desired, so if you're just planning on hitting the restaurants and petting zoo area (Pioneer Hall), your quickest route would be to take a bus from ASMu to the Magic Kingdom, then hop on the FW boat from there. Pioneer Hall is a straight (and quick) walk from the boat dock. If you're against the idea of taking the boat for some reason, then you can take a bus to any theme park and then take the FW bus from there.
To get to the Fantasia Mini-Golf course, you need to get yourself to the Swan/Dolphin first, then you can walk from there. I'd take a bus to MGM and then the boat from there to S/D.
If you want to go to Winter Summerland, you'd need to take the Blizzard Beach bus (which I think is usually the AKL bus). Even if Blizzard Beach isn't open at the time, the bus will drop you off there for mini-golf if you tell him where you're headed. I know because we did this last December.
Good luck!
