Only Fox knows the answer to your first question. Personally I have a hunch all the films survive. What Fox doesn't have in their archives can no doubt be had from another archive. I'm constantly being surprised at the number of "lost" or forgotten films that keep turning up in private hands. There are a LOT of silent and early talkie westerns in circulation that originated at the studios as well as from smaller independent companies that no longer exist. The two documentaries "Fisherman's Pluck" and "Outdoor Adventures with Zane Grey" were officially released in horrid quality on Lions Gate's ZANE GREY WESTERN CLASSICS box-sets volumes 1, 2, 3 and 4. Four films per box, mostly 1940s versions, each with the same home movies. I wouldn't call them documentaries. They're heavy sledding. Some of the films are pretty good; about equal to the Tim Holt westerns from Warner Archive. Out of print now but still available at amazon marketplace and ebay.