David, Q1: Yes
From the instructions: “3A= .42VDC (forty-two hundredths of a volt)”
Q2: Microstepping can reduce resonance, but will reduce torque. From the instructions: “We recommend using 1/2 or 1/4 step. This produces almost full power and usually avoids any resonance issues. The finer the micro step the less power you’ll have. Don’t use microstepping to increase the “precision” of your machine.“