(I think this is current but plz double-check: http://www.nolo.com/legal-encyclopedia/when-is-waiver-inadmi...)
That was in 2003 so I understand the process might have changed. However I don't believe it has changed that much. It was pretty straight-forward (all things considered - some lost paperwork and redoing of fingerprints). I choose to continue on the citizenship path one a baby was on the way and that too wasn't hard.
There are a number of non-profits that help advise in this area. I would recommend contacting EIIC ( https://eiic.org/ ) who helped me navigate the paperwork.
During my process I did NOT need to leave the country and submit paperwork from abroad or anything like that.