Some more information on the User Interface would be good a 4x4 keyboard it a bit open considering the you want the values to be absolute or relative, you need a way to select this using the interface.
Are yo expecting the "steps" of the motor to give you a position based on a fixed calibration point, can the movement be actuated manually, if so then the "step" counter will be out. An encoder wheel on the drive shaft is a better option or a stepper motor with a built in encoder wheel.
I have sent you a PM with some of my other work listed. If I can be of some help please drop me a PM or send to my personal email .
Cheers Pete.