So, could you elaborate on your thought process w/r/t pulling this stuff out into a separate document? Does the README_SETUP seem like a bad idea? Or is it incomplete, or something?

I like the idea of having one install doc rather than two, but don't have any religion about where it should live. doc/ seems ok, as long as there's something in the root to remind you to go there. (What about that old chestnut, INSTALLING?)