Hello all --
I wanted to put this up as the very top post; in case anyone runs into a question or two during the process that I haven't covered, or needs answering, ask me in the comments to this post. I'll respond in a dedicated post below (or, if I get two or three baby ones -- i.e., "How do you pronounce 'Volstead'" and "what year did Al Capone move to Chicago" -- I'll bundle them into one post).
I should respond fairly quickly anyway -- I have a fast computer at the day job and I have fairly good Google-fu -- but if you need it in a particular hurry, do also let me know. As well, if it looks like it's going to be a tricksy thing to track down, I will let you know.
Fire away -- if I can track down the home phone number of the last living relative of William DeMille, I can track down lots of things.