What I thought was interesting about Hook in the finale was that yes, he didn't like his past self and didn't want Emma to see him like that but even more---Emma accepted past-Hook. She had no reservations about flirting or going back to his ship with him--even after being warned by present-Hook. In fact, WHY did Emma go back to the ship with past-Hook? Was it really to see if present Hook was there? I think even present-Hook was wondering about that.
It's true that Regina has evolved and I think that Neverland and Zelena helped her do that. I think we may have even seen shades of Frozen in the Regina/Zelena dynamic--why else make them half sisters? It really did nothing for the plot. I think what Adam and Eddy are saying is that Regina has changed, and, this season we'll see how much. We know she wasn't remorseful in Neverland but perhaps since then she has become somewhat remorseful. Perhaps losing Henry for a year and now Robin maybe forever will finally be the wakeup call she needs.
As for Regina and Henry's quest to find the author of "Once Upon a Time" I still think that this particular book is Emma's story and the people she encounters as it relates to her own story. Everyone in the book has a significant impact on her life. I think Emma's happy ending is in the book but perhaps not Regina's or Rumple's. It makes sense for Snow and Charming's to be in there because they are her parents.