1. Due to the steering setup, I would expect the steering to be seriously affected by the torque of the motor, both under power, and under regen.
2. Two motors can be controlled by one set of controls, but you would need to splice the two control harnesses together as shown in
Gary's video.
I would suggest staggering the joints over a longer distance
(instead of all in the same place) to ensure they cannot touch each other , similar to this extended cable joint:
Alan