[Overdriven]

You said the trans is locked into second, if thats the case and you use a pinion on the motor you don't need to run mech brakes. If the trans wasn't locked, and/or you used the tekno clutch setup you would have to run mech brakes.

One piece of advice, decide what chassis you want to run and the battery location before buying batts. If you buy a 5cell brick, it won't fit in an e-revo chassis and you'll spend more reconfiguring it or buying another batt if you decide you want to go that route.