1) yes, cnc has 2 completely independent axes and commands X & X' so it does the control with 2 independent servos
2) ONE step/dir command sent to both X & X' axis drives: being a position command, the axis drives will maintain the coordination from 1 cnc command.
3) one analog speed command from cnc to one drive called master: then it outputs command to slave drive to follow it. 1 cnc axis to do this too. master is velocity drive, slave is position drive