Here is an important resource that I'll be studying more closely when I re-read Illuminatus! again: an "Illuminatus! Studies" site by together by Bogus Magus that includes a timeline of the book, a detailed outline of the names of the various sections of the work, biographies of the characters, cover art for various editions, an article on the Ken Campbell theater version, a list of other resources (I was very pleased to find this blog listed there) and an article on references to other texts. Lots of stuff to explore here, including a posted outline of RAW's own online course on the work.
All hail Bogus Magus! Official site (Jesus, he looks just like I imagined!) and Twitter account. Be sure you follow the links to find out who was the hidden hand behind the original version of Jabba the Hutt in Star Wars.