I'm off on a trip so probably won't be responding for a while - but I'm glad to hear there is so much interest. Certainly you need to read all the books in Waite's bibliography to know when he slips something in from one of them, but there are many other, non-tarot works that influenced Waite greatly. A few of his references are blind-alleys, where Waite intuited there was an important connection but it doesn't exist literally or in terms of specific parallels - like the alchemical <i>Mutus Liber</i>. It's a "silent" book of images about spiritual transformation, but there's no direct image correspondences as you might expect from Waite's reference to it in PKT (at least, none that I can see).
Well, I'm working on other things right now, but I keep collecting every reference I come across and hope to put it all together someday.