John,
I must admit that even after looking back over this material I feel unsatisfied (or at least less satisfied than I expected). The condensed summaries are too vague to see the picture...and the detailed texts too much info to hold in the brain at once... I'm jumping back and forth, but I haven't yet quite felt like "Ah, that must be it; that's how it all probably happened." I am even still on the fence about whether "modern" chanties generally came in in the 30s, 40s, or even later!