Q3&4
Looks to me as though you're reading American notes!
PPH I think is pounds per hour (most other people used kilos per hour).
Fuel flow demand is the amount of fuel flow computed/required to achieve the desired thrust/torque.
MMV Demand (called for valve position, computed by the ECU, to give required thrust), MMV Position (actual valve position). MMV Feedback (difference between called for and actual valve position, once this feedback signal returns to zero then the engine will be in a steady state).
Can I ask what you are aiming to achieve? I can't help thinking you're digging too deep if you are studying for a B1. On the other hand if you intend designing HMUs then you're on the wrong website!