Alderaan explosion, some of the Battle of Yavin (but not a lot of it), the Sandcrawler, the Millennium Falcon taking off, Vader’s lightsaber correction, the Millennium Falcon being tracked by that dude, [the new Yavin Base shot](https://vignette.wikia.nocookie.net/starwars/images/9/9d/Yavin_4_Temple.png/revision/latest?cb=20121227220518, and one of the new Cloud City shots are all shots I just prefer.
Those are all ‘good’ SE changes to me, so I don’t think you’d need two versions.
As for how long it should run, I’d say let your bladder be your guide - anything running over 2.5 hours is pushing it.