3)
In this case at what safe minimum FL the maneuver (by the same trained pilot) should be initiated (at what FL) to present reasonable chances to recover in time. (before SL
)
In the AF447 case, they could have recovered if they had initiated somewhere around 10,000 feet, maybe even less, but there would be no room for secondary stalls. It would have to be done perfectly, and if you don't have Normal law, then you need an AOA indicator to do the recovery perfectly. Your flight control system can screw you up if it trims the THS too slowly.
Not only that, there is also a 'cornering' speed that you would not want to exceed either. If the aircraft got into g limiting, that would result in less than ideal results.
Once flying (un-stalled), you would want to accelerate using maximum thrust up to the cornering speed and then go to near idle to avoid exceeding it.
One of our aircraft performance guys can probably come up with some realistic numbers, but I have just described the basic tactical approach to the maneuver.