You send copies of everything for the application, but bring in the originals (and more copies) during the interview. I brought a bunch of pictures, his and my original birth certificates, and marriage certificate. The officer also asked for any extra proof or new proof that wasn't submitted - like we bought a car in between the time we sent the application and our interview so we included a copy of those documents. They may retain the copies of things like leases, titles, bills, retirement/bank statements, so make sure to bring copies of those. She also took some of my pictures.

Good luck on those waiting!