Calibrate the pedal or adjust the minimum/maximum range in M-Audio Control Center.
Yes, on Oxygen Pro series (Exp 1 and Exp 2). Assign them to different CC#s. m-audio expression pedal manual
Toggle the small switch on the bottom between Pos. 1 (default for M-Audio) and Pos. 2 (reverse). Calibrate the pedal or adjust the minimum/maximum range