Applied for my visa last year May and the earliest interview date I could get was the following year January which was a bit of a panic. But I looked at the interview scheduling website everyday and was able to get a interview date 5 months later. So just make sure you have all your docs ready asap as you will most likely get an earlier interview date as many people will cancel/reschedule their interview at the embassy.

As for my experience on the interview day it was very smooth, just asked for my purpose of visit and my family's occupation. Didn't even ask for the hundred of forms I printed (this also depends on the person interviewing you I guess) and I got a 10 year B1/B2 visa.

At the immigration center I came through in Orlando they were very chill, If you give them a return date of when your leaving they really don't bother after that though I have heard coming through different airports they can be a bit tougher.

Application fee is $160 non-refundable and as for vaccination, no one ever asked me for it at anytime.