Not exactly accurate. After the initial "What its it?" or "orienting reflex (OR)", the automatic response is fight/flee/freeze (FFF). That's probably 400 milliseconds. To do anything else requires higher cortical functioning, and takes a moment. So no... our brains do not jump into the flee reflex at the last moment... they jump into it at the first moment.
No, I mean the stage in front of that. If you evacuate by waiting in the evacuation line, you are still rational.
You can not learn to do this with any mental rehearsal alone.
Yes, but again, with actual training being unpractical; that's pretty much all you can do.
I mean I can just enroll in a helicopter crash training (that's just off-shore work certification, but open to anybody), but you can't for an airliner.