1. Cloud is the same all the game
2. Jenova didn't controlled anything
3. IHMN is right! Sephirot controlled the other 12, and the "Winged angel" you fight is the real Sephirot. Don't you love it?
4. Sephirot was never controlled
5. I won't spoil about Cait Seith. It was specifically stated in the game.

It brings back beatiful memories.....
Now, I'm going to my home to play FF7 for the N'th time.

Bizzaro Exdeath did an awesome plot analysis about five monthes ago:
The Final Fantasy 7 Story Guide

That was a wonderful analysis. He obviously did his reserch. I had a question, but I know the answer now.

I'm gonna say this now. I have never played any final fantasy aprat from 1&2 dawn of souls, and kingdom hearts. But I know loads thanks to http://www.ffcompendium.com/h/ I think I put this somewhere else. I'll admit there are some things in FF7 that were never explained, but those will be answered in the movie. Oh, and the kingdom hearts cloud, so much cooler.

only one thing
 

I can really only pitch my 2 cents in on one thing. My belife is that the reason that Past Sephiroth is so different than Present Sephiroth, is all the time he spent in the lifestream, that had to increase his consiousness, and since he wasnt your average human (even though cloud wasnt, he was nothing compared to Seph) it couldve had a different effect that it did on our hero, Possibly giving him the knowledge of ages! Wasnt that what materia was? Crystallized knowledge? and Materia is made from the life stream, so.... I think he learned alot during his "death" and I DO support the idea that the lifestream carried him to North Crater, since it WAS going there to heal the wound. Well thats all I got!