Well I've been in game about 6 months so I'll give it a go, the worst that can happen is I am wrong.
Answer 1, I would think this would be speeds and climb and turn rates which the given plane performs. Like max climb rate, sustained climb rate, max speed in a sustained turn, ect, ect
Answer 2, As I understand it, this is basically lift in the direction that your head is pointed?? Like if you are in a turn and your plane is at a 15 degree wing angle then you lift vector would be up, and at a 15 degree angle as well.
Answer 3, I would say any turn less then 90 degrees at your particular planes best turn speed or faster
Answer 4, Here to me I guess I would say any turn in excess of 180 degrees at best turn speed or lower for that ride.
Answer 5, disruption or loss of airflow over the wing (s) surface. could result in a spin. loss of lift causing a fall in the direction of gravity

, 1 wing may drop off, could result in a flat spin, nose can drop, or could result in loss of forward momentum.
Hopefully I got something right or close to right.