Again, I'm disappointed that someone as famous as Down's does not have a suitable biography. The Canadian writer who wrote the intro to Modern Coin Magic (Dover paperback) did a good job gathering additional info. He even stated that he was working on a biography but, alas.
I will look at the Vernon bio by Ben. Also, I may renew my membership in the people who have the Ask Alexander database; I signed up early at the lowest membership level and they never supplied me the info I need to sign-in to the database. I don't know if the $95 membership allows access.
Regarding the notebooks, I think there were only one set (I could be very wrong about this). They were assembled by C.R. "Bud" Tracey of Sioux City Iowa who I assume passed away in the late 1980s or early 1990s (a guess on my part). Last month this is what Mr. Hatch wrote about the notebooks (scrapbooks):
According to the 4 page article by C. R. ("Bud") Tracy, who made the scrapbook, at that time (1974) it consisted of 45 acetate 8.5 x 11 inch sheet protectors, for a total of 90 pages. Mr. Tracy continues the article with a detailed description of the contents which included photos, letterheads, businesscards, programs, correspondence, 6 inches of a Pathe News reel film of Downs (the original 300 feet had disintegrated), membership cards, newspaper clippings, telegrams, tokens etc. An few pages and items from the scrapbook are shown. The scrapbook was assembled by Tracy (not Downs) for display at a magic convention. Tracy was a very good friend of Downs, probably his best friend in has latter years, and inherited much of Downs' memorabilia, as I understand it. I have heard that Tracy's Downs collection was willed to the Magic Castle, but don't know if that is true or what the current status might be.