He took so many risks, man and Fox were prepared to axe the movie because he was going over budget, and they assumed it was going to be a flop.
I've seen a couple of Docs on it, but my favorite is Empire of Dreams, which is all about the model makers and designers. So good.
I read somewhere that the Empire was actually based on America, but maybe heavily militaristic superpowers in general. I did see that the Ewoks were based on the Viet Kong. He wanted an "I'll equiped" almost primitive people to take on and topple the more sophisticated Empire.
Also, the world's going a bit nuts now, but there is one silver lining, during times of strife and recession, art is the one thing that prospers, so within the next few years we may see and hear a lot of great stuff, which is something to look forward to.