It's a bit wordy, but this article about the silly retcons GL made to the saga in the prequel movies that led him to "fix" the "errors" in the original trilogy is pretty insightful:
http://whatculture.com/film/10-star-wars-retcons-dumb-actually-hurt.php
On the point about the lightsaber battles, I'm really shocked that Lucas has found a way to "speed up" the Obi-wan/Vader duel and add backflipping Vader and Alec Guinness!
Wow. I had completely repressed the memory of Artoo flying.
It is unbelievable that I live in a Universe where the PT can exist.
In terms of what he is for it makes sense that Artoo has jets for directing himself in space which he could use for small hops (think the EVA pods in 2001).
The only time he might have used these in the OT was in the Dagobah swamps where swamp gas might have prohibited it and maybe on Jabba's barge but he wanted to nudge a reluctant Threepio.
The way he uses them in the PT however is very silly and the EU explanation for why he doesn't use them in the OT is even sillier.
This is why the PT and anything that reeks of the PT (including the objectively better Clone Wars series) has absolutely no place in my personal canon and never will.