S-64 Rear Seat Controls
Shawn has the control orthogonality correct. As to the question about "full authority": the rear cyclic acts thru the AFCS for pitch, roll and yaw. It has +/- 10 % authority, and that authority is shown on a cross pointer indicator. The 10 % control range can be shifted by utilizing the rear cyclic beeper trim, and the pilot can see where he is on the cross pointer indicator. "Back in the day" they'd make you fly around the pattern backwards from the rear seat before they'd sign you off.
Thanks,
John Dixson