It was so not as scary as I thought it would be. We e-mailed the consulate beforehand asking permission for myself and child to accompany my husband to his interview. They said yes and asked us to print the e-mail and bring it along with us to show the guards. But once we got there, they didn't even ask to see it. In fact, we received two checklists from NVC asking us to bring paperwork to the interview with us but they didn't ask for any of it. They did ask to see a tax document that NVC said nothing about, though. Luckily I had it!
We also brought our 21 month old with us to the interview, and they didn't let us bring our diaper bag upstairs with us. They let us take a diaper, wipes, and markers and paper to occupy him though.
The process took about an hour with maybe 5 minutes spent talking to a very friendly woman who organized our paperwork and another 5 minutes talking to a very friendly man who interviewed my husband. All in all, it was a good experience.