Good rundown! I agree that the Folio is probably most essential - the Captain and the new potion table are probably the most game-changing additions. There's a complete list of Frostgrave material at the designer's website, including some scenarios and rules published as magazine articles: therenaissancetroll.blogspot.com/p/frostgrave.html
The various pieces are in PDF... except for the last bit which was exclusive to this printing (afaik). I think the exclusive bit will eventually hit PDF (don't quote me).
Just wanted to drop a comment here in case you missed Joe's reply above. "The folio will be available as an ebook on the official release date later this month."
