Part of the slow going may be due to multiple weather problems since November with ice and snow. That may (and has) slowed the process some. I know that half, or around, the admitting class come off of the waiting list. Each round of interviews the adcom reviews all of the applicants up to that point at the same time, waiting list and those interviewed that round and some are pulled off along with acceptances from the interview groups and offered a slot. As to how many they will interview, no clue. Last years was around 250 or so and most admits are from in-state. I know this has been rehashed a couple of times but hopefully it helps some.
**Disclaimer** My information comes from many who have attended OSU-COM and what I have gleaned from speaking with them.
Good luck to all of you.