i ride like bit of park (even though it is shit) and fr i aint ever used a front brake even though got a set of mono minis i dont use the front there is no point i can keep up with ma m8's with them on like single track it is more fun u go faster coz u dont wanna lock ur back brake if you dont have one there is less to brake
but for cross-country, downhill, freeride, and road you definately need them, it slows your bike down very fast and its easier on your tires as you won't be skidding as much.
erm barspins and such are easy doerble i could barspin (i carnt but i could if u get me) becuase the cable was so long but front brakes are gay so dont use one for dj ur just guna brake it