(1) The track power black goes to the wheels (frame), and the red wire goes to the center track rollers. The front and rear rollers are connected together to go to the red wire.
(2) I suspect that's the wheel connection for the track power unless there's a specific connection from the trucks.
(3) You need all three boards. The board on the end of the cable is the RailSounds power board.
Pretty sure these are the motor on the TMCC board.
