As long as you are using transistor type PLC, you can use any output as your high speed pulse generator. Although i’m not sure yet about the frequency of each output. In some cases, Y0 and Y1 can give you the highest frequency and the rest is slightly slower. You can check the datasheet for the frequencies.
Most of the industrial stepper/servo driver are compatible with the plc. What stepper are you using? Oriental stepper motor? Most of the stepper driver are 24V as most industrial controls are 24V. Though i haven’t checked yet if there is an internal conversion within the circuit. As with the sinking/sourcing, moat controllers have a switch or jumper to select between PNP/NPN together with the switches for the selection of type of input signal (+/-pulse or pulse/direction)