Teal -
1. It's gusty all around the world, in different places, all the time. The engines are designed for these conditions.
The engines did not stall. They stayed at the power setting they were at. We don't know what that power setting was but obviously it was lower than was needed.
2. Ah, this might be the heart and soul of the investigation. What happened? We don't know.
It's not common at all. That's why this is such an interesting event for professional pilots.
Years ago RR engines on 757's had what we, on the sunny side of the pond, call 'deep idle stalls'. What were the symptoms? Push the power up and the engines just stayed at idle. Obviously it never developed into an incident. Is that related to this event? It's waaaaaay to premature to suggest any link between the two.