From what I've read it's not a straight g-load setup, but I'll defer to those who know better. Your A320 seems to have a safeguard against NU trim when the Stall Warning sounds, and why this isn't the case for the later widebodies is absolutely a question that should be put to Airbus.
yes, correct. It is normally a mix of g-load and pitch rate. More pitch rate at slower airspeeds, more g-load at higher airspeeds, with a crossover point where both influences are equal at an unpublished speed - probably somewhere around the greendot–250 kts range.
However - in a stall recovery scenario (as opposed to the avoidance scenario), there's no way the SS should be neutral - it should be commanding ND in order to effect a recovery.
And in Normal law it does. But this was a degraded flight control law with no protections (except g-load) left. Normal law would prevent the need for a "recovery". Due to some questionable design choices, AOA was deemed unusable with indicated airspeed below 60KIAS—so, there's nothing left to drive that pitch down except a pilot's training. (but when that pilot's training for stall recover consists only of full power application during stall training at 5,000 ft—there's not much there to help either!)