Feigao 6L help

[JUS4SHO]

i just aquired a Feigao 6L motor for my slash 4x4 , with a vxl-3s and i have a few newbie questions
1) what gearing should i use? can i run 15/50 safely (i plan on using a doule integy fan on the motor)
2) this should be faster than the stock motor?
3) the wire colour code does not match than of the vxl-3s how do i wire it up

thanks in advance for all the assistance