So you should have everything you need to run the car now, right?
I've heard about the superbrain being decent, and yes your cells will get hot/warm by the time they're done charging, so don't freak out.
Hmm I don't think anyone responded to your question about the spur and pinion gears. The pinion gear is the one on the actual motor. Stock, I believe it has 19T. The stock spur gear on the TT-01 is 61T. This system works as if you were driving a car with one gear. With the different combinations of spur and pinion gears, you can get a desired handling characteristic. Motors of this size have some pretty good torque, so really low gearing in my opinion is unnecessary. I am running 21T:61T since i got the 20T and 21T pinion gear upgrade from Tower.
Note that pinion gears and spur gears are bought SEPARATE from each other. I believe they have a spur gear package that is 55T and 58T, but Tower does not stock those
Have fun!