I applied to 3 O.D. schools and was accepted to all 3. My impression was that as long as you have shadowed an optometrist and know a lot about the profession and you've got decent grades and OAT, then you're Golden. Any other extracurricular activities are not neccesary solely for the purposes of gaining admissions. If however, you have a less than solid GPA or OAT, then you need to have some other good things going for you (ie. more extracurrics).
I think the interview is similar to med school interviews (though I have never had a med interview). I think the optometry one is probably more laid back though. The type of character they look for: Someone who is comitted to optometry, is passionate about it, intelligent, calm & relaxed in the interview and generally seems good natured and friendly.
My 2 cents...