1) There is no evidence of gross pilot's incompetence.
Actually there is, inability to keep airplane out of stall regime is such evidence. Absent obvious excuses like smoke, fire, flight control problem, incorrect PFD readings, in-flight break-up it is inexcusable. Correct engine identification or lack of is actually quite secondary at this point. No regulatory agency grounds all pilots and send them for simulator check-up without having pretty good idea what transpired.