Finishing brushless LST, some problems I need help with

[Robl45]

I'm finishing up my brushless LST2 and have a few problem I'm hoping the people here can help with.

My throttle/brake servo moves more when pushed to throttle than brake, is that normal? My brakes really aren't working too well now. I checked all the settings on the radio and everything seems normal.

Next, I have no idea where to mount the speed controller. There doesn't seem to be a lot of space on the chassis.

Finally, the motor is stuttering when starting up. I'm using a bp hobbies 100 amp esc. It has settings for timing and frequency. I have it set to 8khz and I believe 3 degrees timing as I"m running a feigao 11xl. Should I try different settings?