AOA is a bit different here. At the current moment, it does factor in our Mod2 grades a bit (the organ blocks, not the basic science-y stuff you'll start out with), but with most of the emphasis on clinical grading. Now, clinical grading is not done by "chunking". This means, anyone can get honors/high pass if they do the work to deserve it. There's not a hard and fast limit on percentages of each designation. As for AOA, there is an "internal ranking" system. The top (I forget the exact number)% are allowed to apply for AOA each year at the end of 3rd year. At this time, everyone submits their applications including community service, extracurriculars, research, etc. There is a committee that uses your rank, activities, etc and picks AOA from there.
As the years have gone by, more and more emphasis has been put on the extra stuff. Grades still matter of course, but they are not everything!
We also have the Gold Humanism Society which is completely separate and relies on basically everything except grades.
Hope this answers your question! If you want more specifics on anything just let me know.