Just a little bit on the servos speed thing.
normally the fastest servo and the highest torque are normally the same servo with a different "gear" ratio. To achieve the higher torque the load that can be applied to the final gear is higher, however the failure will normally occur at the lowest surface area to torque ratio (which may not be the final gear), Ironically the faster servo passes less load back through the gears and by theory should be the tougher, but that weak point can't be determined by the stats on the box