1/ you might be better to research Manuf. that offer non-dedicated systems, i.e. various makes of motors can be used with their drives. For eg A-M-C and Copley Controls and Aerotech.Originally Posted by GalaticDan
2/ AC Servo Drive & Amplifier usually indicate the same thing
3/ See 1/
There are many types of AC servo drives, if you want step & direction I believe you want the PWM type, these work with digital controllers and use a TTL input for PWM & step and direction.
There are usually many of the above makes come up on eBay regularly.