DRV8823: DRV8823 usage problems

Part Number:DRV8823

A project adopted DRV8823 for the mechanical moveable parts driving. Few questions require TI’s confirm…

Both DRV8823 and it tied motors are driving with 12V voltage now, but the selected motor only accepts 8V supplying.

1. Does the DRV8823 work in constant current mode no matter motor supply voltage? Or the supply voltage rating still affects the torque and acceleration of the motor?
2. AM I via FW configuration to adjust the DRV8823 control RPM and torque?