Bldg 14, in AB section, is the very closest bldg to both the food court and bus stop. We were in that bldg, ground floor, corner room, and could see the buses coming and going through the trees. The rear wall of the main bldg was across the walkway from our room! But, this is a very popular bldg...there just happened to be a room that would be available later in the day if I wanted to wait for it..which I did.
I would call whomever you booked your room through, and put in your requests...close to food court, bus stop, possible on the ground floor, especially if your f-i-l will be in a wheelchair for the parks due to the walking issues. The walks, from the rooms, to a bus stop are not all that bad. It can be about an 8 min walk to the food court from the further out rooms...we had one for our first trip.