I wouldn't have thought your wishes can come true by changing Send, Save, or Plugboard templates settings
Maybe the series one could be done with a template function - it's the last item in Preferences.
I assume My Rating is a custom column, what happens if you tick the half stars box in the custom column definition (that assumes a 1-10 rating), a 3 should show one and a half stars in the book list and book details, does that not show up in the jacket?
BR