The most important thing to anticipate is the legendary NYCOM goose poop. Everything else is secondary to this.
The interview, from what I remember, was VERY low pressure. I was interviewed by both a DO and a PhD simultaneously, and mostly I was asked about things I said in my personal statement and other items in my AACOMAS application.
The secondary application form basically asks why you want to be a DO. You can prepare a few ideas before your interview date and just write them on the paper when they give it to you; you'll have plenty of time to write your response.
You may not have to deal with the "goose poop" in quantity for now as the school is doing alot of major landscaping work on campus, they totally ripped up everything and started over. It will look great when it's done, but for now, the geese have been displaced. I'm sure you'll sleep better.
For the interview, dont sweat it. Stay relaxed and know a bit about the history of osteopathic medicine (try to refrain from using the word "osteopathy", as they're trying to do away with that word), and why NYCOM in particular. Tell them you're impressed with the technological advances NYCOM has and the quantity and quality of clerkships in 3rd and 4th year. They should bite onto that.
The OMM room has been around awhile, but it is as state of the art as they come. More recent advances include all students receiving PDAs, the streaming video online that enables you to watch any lecture from home, and the ethernet connections at every lecture seat and most study cubes. Supposedly they're going to go wireless soon so you can bring your laptop anywhere on campus and connect.