Wet signature is not required.
Yes, we have done our entire process ourselves. I recommend reading as much as you can about the process. Mistakes can add time and money to a process already fraught with roadblocks.
If we were to do it again, we would definitely avoid the K-1 and do a CR-1. The adjustment of status part of a K-1 is a huge drawback. With current wait times, your fiance may not be able to work or travel for up to one year. The green card can take two years, and removal of conditions is up to four years. In many states, people without green cards cannot drive.