Vilas,
2. If ATHR is disconnected from FCU, thrust will freeze in the present with thrust lock and ECAM warning.
3. If ATHR fails it will freeze with Thrust lock and ECAM.
Not necessarily, See 22,30,90: Thrust Lock Function
"The Thrust Lock function is activated when the thrust levers are in the CL detent (or the MCT detent with one engine out), and:-
The flight crew pushes the A/THR pb on the FCU, or -
The A/THR disconnects due to a failure.
The thrust is locked at its level prior to disconnection. Moving the thrust levers out of CL or MCT suppresses the thrust lock and gives the flight crew manual control with the thrust levers."
I prefer the FCOM explanation thanks.