Fang Zei said:

Did Lucas give any input on the the Thrawn books back in the day? Who got the ball rolling on the idea of novels set post-Jedi? Why didn't it happen until 1991?

The biggest question, one we can't really know the answer to but is still puzzling, is whether GL honestly never intended to make Episode 7 as of '91 and therefore said "sure, do whatever you want, RotJ is the end as far as I'm concerned."

This is a great question. I know the word Coruscant was made up by Zahn. I'm not sure why they didn't use Had Abaddon which was the original name for the Imperial homeworld in the old drafts.

I think back in 91 he had no intention of even making the prequels so he was fine with the sequel novels. His usual answer to more Star Wars movies was "someday" and "when the technology was right" but I think he was torn on it. I read somewhere that it wasn't until a financial meeting with Lucasfilm investors that it became imperative that the prequels should to be made for revenue.