Jammin X1CRT

HI Everyone my account finally got processed so my posting can now begin.
First off Im building a Jammin X1CRT im going to be running off or 5s lipo, a Medusa MR-036-060-2000V2-5 off of a Monster Max esc *preorder was done this morning :)*
My question is on what size of pinion would be best I will be racing my beast this summer. IM actually looking for 3 pinions one for short tracks, one for a good all around setup, one for top speed.
Do you guys think it will be worth the wait for a slipperential ?? Im heavily leaning towards one when there released.
Does any one know what gears these will be running? Mod1? or 48 pitch?
my last question should I use the motor for brakes or use the stock stuff?