How does an elevator offload function works in fly by wire flight control systems?
Regarding the first point, from Lufthansa Technical Training Manual for 777, page 30:


  Elevator Offload Function
  Operates only in the AirCommands to Determine when the Elevator is not at the Neutral Position for more than two seconds minimum.Commands the Horizontal Stabilizer to move as a Function of Airspeed. The Movement of the Horizontal Stabilizer then causes the Elevator to move to the Neutral Position