Get which ever one you like better. I would get the brushless version as it will save you some $$ down the road. Remember....the faster you go the more you break so get it and have fun.
The auto correction will make the truck easier to drive and is WaYYYY worth it. I wasn't sure but then I tried it and i think it is awesome and you can turn it up, down or off to your liking.
Both are good. Tires are a little larger on the big rock so may be better for a construction site but you can always put bigger tires on the vorteks too.