These skis don't have any rocker, so if that is what you want, I would click on some other skis. Ones to look at might be like an Armada JJ or ARG, Atomic Bent Chetler, 4FRNT CRJ, or Rossi S7. The hellbents are cool, but unless you are balls deep in pow, they are not the best choice. As far as length goes, I would hesitate to dip below 185 with a rockered ski, at 6ft, anything shorter will feel very squirrely.
Mounting position depends a lot on your style of skiing, how much switch riding, buttering, etc. you want to do, as well as the ski itself. If the ski is symmetrical, then a true middle mounting will work best, otherwise anywhere between +2 to +5cm will allow for a good mix of stability, flotation, and maneuverability.