Power windows are extremely common in almost every single modern restoration of any film that was photochemically graded. If the goal of this is to make the “official Blu that never was,” power windows would really just make it even more “accurate” to that goal. I don’t see an issue with them, frankly.
In general, yes, but there are some specific atrocious examples. I believe Harmy already dealt with a brightened Vader in a hallway shot on the Blu-ray. I imagine that any alteration that just plain looked bad would be worth fixing. Just like a wipes might not be redone in general, but a wipe would be worth redoing if it showed the SE version of Ben’s hut, for example. There’s a lot of judgment calls, and Harmy’s standards are always more stringent than my own, so I’m good with whatever he does.
Oh, Harmy, you’ve got to snag 44rh1n’s FOTR regrade, it’s excellent!
Quoted for truth.