Actually, now that I have thought about it some, you might not even need to bother with Nook for PC. I mean, assuming that the notes and highlights exist SOMEWHERE in the epub file, you can probably get to them using either Sigil or Calibre (especially Sigil). But it wouldn't hurt to get Nook for PC anyway, of course. Sometimes it comes in handy.
I am actually interested in what you find out when you try to get your notes and highlights. I might want to do the very thing you did, and I'd like to know if the results are available for capture myself. So please report back anything you find out.