1) Yes. The ending of X3 where Storm is the headmistress of the institute is enough as to why it would "make sense." Not to mention she is actually in the story, and faces the best chance against the Sentinels, providing some cool-as-**** visual effects.
2) I don't know. But, a younger Storm in the 70s would be great, and even better would be to have both a 70s Storm and a future Storm.
3) Yes. And if he doesn't, I will shake my fist ire!