On the HMC website, it says that they hold interviews between May and December, but doesn’t that mean RD applicants won’t get an interview?
You can ask for an interview if you go on a campus visit. I’m not sure if they do remote interviews of some kind or not these days. But you don’t need to interview to be accepted (my kid didn’t interview).
I think they are really too busy with application review between Dec and May. It isn’t like an Ivy where they grant interviews only to some applicants. If you want to interview,you need to ask for one between May of jr year and Dec of sr year. If you missed that window, I would not worry about it. Lots of the students they accept didn’t interview. You may not get in, but no interview probably wouldn’t be the reason.
That’s a relief! By the time I realized, the last couple of slots were already filled 
@intparent can I private message you about a concern I have about my HMC essays? (i know the deadline passed but I’m worried).
I don’t read essays, but am willing to answer more general questions about them. 
@intparent I didn’t mention anything about the HSA in my essays, and all my extracurriculars are stem focussed. my low sat reading score doesn’t help either. Would I be viewed as not a good fit?
I don’t think my kid commented on HSA, either. Hard to say how they will consider your app as a whole.