Zen asks, “Do we still need to bring a letter of intent to the interview?”
What we recommend is that you take an entire copy of your petition to the interview. It’s not always required. They may not ask for the documents. The reason to take it with you is the letter of intent is provided at the USCIS stage with your initial petition and paperwork, but I would take a copy of it just in case the consular officer asks to see it.
I know, when I went to the interview with my wife, we took quite a few documents and supporting evidence, and the consular officer didn’t ask to see any of the items that we had, but we did have them there just in case.
It’s good, just to have a copy of the original petition on hand in case any questions come up during the interview, so you could always reference to the petition.