I can’t speak to the registration, but I just converted my license and to echo the other comments, the document verification guide on the website was very helpful. If you have a passport, license, SocSec card, you’re all good for the ID verification; if you don’t have a passport you’ll need to go to alternative ways of proving citizenship, like the birth certificate. You only need one proof of residency–if you can’t dig up your lease and your utilities are included (mine are), a copy of your renter’s insurance policy will also suffice. I actually found the whole process efficient and the staff were all very pleasant. I went to the temporary C St service center at 9:00am on a Wednesday, and was in and out within an hour.