dtam:
I would try going a spring softer and 10wt lighter oil all the way around;
maybe try a one way;
that servo is fine for stock
the manual has good starting points for gearing, go up/down teeth based on your speed, heat, runtime (well, this shouldnt be so true anymore)
At this point, it may be best to grab a good set up from somebody and practice and race with that for a while to concentrate on driving and learning what the car can do before getting too deep into tuning.