Ah yes, I'm extremely sorry! That is true! I think in my overwhelmed brain I was just lumping those all together so that in my head I remembered you basically get "stuck" in one place for about half of the year. Sorry if I misled anyone! I'll make sure to double check anything else I post along those lines.
I don't know this for sure, but my impression is that they submit a response based on your interview and that they are not part of the actualy adcom. The people who interview you are VERY busy professors and docs, so I imagine that the actual decision comes down to the admissions office folks. I haven't ever asked that for sure, though. Either way, the interviewers will certainly make their impressions known, so the interview is extremely important!!