RE: [Awaiting Approval]
Hi. Cool ride. I like the rims.
Your gearing problem is hard to fix online. Didn't your car come with a instructional DVD from HPi ? The DVD explains all of your gearing problems you might have. Your braking problem could be your linkages near your carb & the one that is attached to the servo. Maybe something is loose or moving too much. There should also be a small screw on the side of the engine near the carb to adjust how much the carb stays open when you brake.
Or otherwise you can take your car to your local hobby shop for advice.