Rubber bands to get you off the line. You are going to need very aggressive gearing for a high top speed but low torque. Rubber banding to collars mounted on your drive shaft with regular (not set) screws in them should be a good anchor for your rubber band. Then you just pull it back some and let it go. You should be able to build a car that can launch well just off of rubber bands, and then add in the motor.
For your free spinning wheel, try to make it spin as long as possible when you flick it.