Steering appears to be a servo with left/straight/centre positions only on front. On back is a drive motor which appears to only have one speed and can go forward and back.
The motors are sealed up in the plastic and i was hopefull i wouldn't need to break it open so I don't know what size they are.
For the thing with the 5WR5J both of the motors wires go into that before going to the other board. Both the blue wires to the motors come from the main board. I think are connected to the points labeled "m". The drive motor to the m in the bottom right and the servo motor for an "m" between the 2 metal plate things which is obsured a bit in the picture.
Power source is a 9.6v 750mAH battery.
"oscilloscope traces of control signals" - I don't know how to do this and don't have an oscilloscope.
Note the board also connected via a single black wire that had some headlights that flashed, but I cut it out because It was molded into the plastic top which I was getting rid of. The car still runs fine on remote control.