Skid steering vehicles like R2D2 setting

How can I configurate in the “Mission planner 1.3” a rover like R2D2 so that when the direction from a waypoint to another is bigger than X degrees (30 degrees) the movement to the next waypoint to be made with a stop than the rotation of a wheel forward and the other wheel backward. I also want to know how connect Pixhawk 2.1 to a SmartDrive DC Motor Driver Cytron MDDS10A. By the way, I’m a beginner so please if you have an explanation write it step by step.