Thrust Reverser Readings
 

When the thrust reversers are activated after landing does the reading on the ECAM indicate idle or does it indicate the actual reverse thrust being generated?

Also, what would happen if one was to engage the reverse thrust below 80 kts or if the engines were at idle? Would there still be any "Reverse thrust"?

N1, N2, N3, EGT etc all read normal, if EPR is used then that normally disappears on a glass cockpit type and you get amber/green reverser indications.

You can engage reverse sat on the taxyway if you wish, standing still, they'll still operate. We (CX) on the 744 only use idle reverse and auto brakes, you still get reversing action! but less than if you applied power.