At 341 pages, this is a major source for recent research. All the papers are in Portuguese, but each has an English abstract, and you can cut & paste text into a translator website (I use Google's). Here are a few papers I'm planning on reading more carefully.
Villa re-used his own music throughout his career. I'm especially interested in the Magdalena story.
This chart will be useful!
This article looks fascinating! It's not often I have a chance to connect Villa-Lobos and Canada. This is an examination of Choros no. 6 and the Introduction to Choros in the light of R. Murray Schafer's "Soundscape" idea.
I'll let you explore the rest on your own. I expect I'll be posting about some of these ideas over the next few months.