Yep, he "purchased" it. What became know as Pixar was indeed the people at the Computer Graphics Division at LucasFilm. They are the ones I call founder.
My understanding was that he purchased Pixar from Lucas for $10mm when Lucas didn't think that there was going to be a very lucrative animation business.
This was told to me by employees of ILM when I was building the letterman digital arts center.
I think it is because Pixar wasn't originally an animation studio. In particular they didn't intend to produce movies themselves. When they became one, he was a founder.
No, they were a part of a company that was almost a studio in of itself. The people that started that division with Lucas, that was eventually purchased by Jobs, wanted to make movies from the beginning. It was their stated goal at the time and they repeat the claim today. It was Jobs that had other ideas for the company, people, and technology before Toy Story came to be.
