Which leads to a post I made last week - why don't they fit AOA instruments?
The difference between "the bird" (the flight vector symbol) and the pitch reference on the PFD gives you the angle of attack - if you are aware of it.
If stablizer trim is full nose up (why is not important at this point) and TOGA is applied - does the elevator have the ability to overcome the consequences if full nose down input is made and held (without changing stabilizer trim)?
No - for any aircraft with this configuration, the stabilizer is more effective than the elevator, and easily overpowers it, especially with the added pitch up moment from high thrust.
There's a stall warning at 2:10:51, then the report notes that the stall warning horn stopped at 2:11:40, the clear implication being that the horn was sounding throughout the intervening period. So the instruments could not have been telling the PF he is overspeeding, as the instruments clearly thought he was stalling -- and saying so.
Stall warning comes from the angle of attack sensors, not the airspeed indicators - so a stall warning with an indicated high speed is possible.
Or is pitch calculated from the l@ser ring gyro and AoA via an aerodyamic sensor?
That's right - in the pic below (this one from a Boeing, but airbus use the same systems) you see two pitot tubes which detect airspeed, and between them the angle of attack vane, which detects the direction of the airflow (and thus the angle of attack).
The inertial reference system also supplies vertical speed information, along with ground speed - so the vertical speed is independent of any air sensing failure.