I operate PS3 locomotives under DCC with my NCE 10-amp ProCab. You get all of the features under DCC that you do with DCS. All 29 functions are mapped. You can adjust the speed curve and acceleration settings on a PS3 locomotive just like you would with any other locomotive with a DCC decoder. MTH provides a manual with all of the values for the CV's that you want to rewrite.
Why on earth would you want to change directions with a locomotive in motion? That sounds like a recipe for disaster to the running gear and motors.