Fett fan-service did start with the special edition of ANH, when Lucas cramed in the scene with Jabba, that is redundant ...
and yes, the Madalorians should have been some kind of threat in the prequels, at least a shadow that was defeated in a war before
as for "Revenge", Luke had many foes to battle, Fett wasn't "big" enough, think Jabba, Vader and the Emperor ;-)
Force ghosts: I had a thought about how and why Anakin could be seen - maybe it was not him to learn, maybe Yoda or Obi-Wan felt in the Force, that he had really turned from dark to light and collected his spirit, to say a last goodbye to Luke before they together become one with the Force - so the "old" Anakin makes more sense, then a juvinated one ...