Premedapplicant,
I can't answer all of your questions, but I can tell you what I learned when I interviewed earlier this week. The admissions woman who spoke with us told us that there had already been applicants this year who were deferred but are now accepted. I don't recall her specifically saying how often deferred applicants are reviewed, but I am assuming it is fairly regularly since there have already been applicants accepted off the list this year.
I would say the question about the update letter is a good one for the admissions office, but if I were you, I would send it in. Unless the secondary application specifically asked (i.e. you checked a box that said that you will have fulfilled all requirements by matriculation). I can't remember if OSU's secondary asked this or not--it's jumbling together with some of the others, sorry! Hope this helps.
