The first FF movie, yeah "The Spirits Within" isnt that one cartoonish?
I think having actors would mess up the movie. It just wouldnt be as good. IMO.
Yeah, I was confused too about the whole Mother Jenova thing. But I read some summaries and stuff for the movie online, and after watching the whole movie for my 10th time, I FINALLY figured it out.
I think they just wanted to find Mother so that they could re-created Sephiroth, as if you remember which did happen at the end with Kadaj. You should really listen to the first chapter in the movie when Marlene explains it all. It made some things clearer for me.