To answer my own question...and check to see if I understand...i have included the following functions:
1. start the motor
2. reverse the direction of the motor - like a reverse gear
3. do regenerative braking
4. regulate the speed of the motor
Is this correct? Are there any others? Is it possible to get a dual voltage controller, i.e. has a switch so that you can use 24 volts and then switch to 36 volts in the need arises?