framer;
Well I think first of all those are good questions to ask and would be challenging for even Airbus pilots to answer because these are flight regimes with which most would notbe familiar. Lest some take from that statement the false notion that there are pilots out there "who do not understand their airplane sufficiently, these control laws are at the very edges if not beyond the normal flight envelope and are in test-pilot and engineer territory where no airline pilot has a right to be.
The actual calculation of the 'g' load could be done quite easily - I imagine that it's a matter of inserting the knowns (TAS, pitch rate) into the equation but I am not a mathematician or engineer so will leave the rest of the answer for someone who is qualified to respond.
As stated, the elevators were already fully down to the stops. We don't know whether they were effective in reducing the 'g' load or whether the high speed and high THS angle made rendered their deflection less, or even not effective - that is a question for another Airbus engineer. Is there something to learn from the last eight seconds or so? The first people to answer that question will be the Investigators.
To the point many have brought up here however, is there something to learn regarding C* Laws (traditional name for fbw laws) or are we in territory so far outside the envelope that engineers cannot reasonably be expected to design a machine that is crash-proof. We must keep in mind that despite vast misconceptions on the part of some, especially those who do not fly the 320, automation, fbw and control laws do not make the airplane crash-proof nor was that ever the claim, nor would it reasonably be the expectation of flight crews.
The next question that is naturally to be asked however is, let us say that the control law did do as it was designed and limited the 'g' load to 2.5g's. What then, in this particular accident? Given a higher altitude, was the aircraft entering an increasing fugoid response which would have eventually exceeded either the airplane's or the crew's ability to regain control? We simply don't know.
Control laws are designed to take maximum advantage of the airfoil while keeping the aircraft out of the stall regime, (although high 'g' loads will pass the flight control computers to "alternate law, restricted or unrestricted"), and/or keep the structure within certification design limits. Must these same laws also cater to those circumstances where there may be insufficient altitude to recover?
That is about the limit of what I can say to someone who doesn't fly the airplane and it is getting close to the limits of my knowledge as well. Best leave the question open for others more capable than I to have a go at.