1) I would call the SA and ask, but I don't think it would.
2) Saw a recent post (yesterday?) in the 7 seat room about someone adding FSD and EDD window was bumped up almost immediately. However given my EDD's I put about zero faith in those numbers. So.....maybe ? lol
3) I would also ask your SA on this, but I suspect the total would just be adjusted. I've learned my lesson and I won't be applying for re-financing again as mine is set to expire for the third time.
With all that said I am considering adding FSD at this point as it looks cool and if there's any chance it will speed up delivery.......who goes first, you or me? Haha.