Personally i think that you can't go wrong with a front disk and a rear rim brake.
I use a Maggy Louise disk on the front and a HS33 on the back, gives me a very responsive brake set up.
it depends on your riding style really, if your looking to get the power down on big hops you'll want one of the longer frames, for more technical manoeuvres I'd recommend one of the shorter frames. The 010 Zoo Lynx is a good overall frame and is in your price range