First off yay @carolinamom2boys, summa is an amazing accomoplishment! Congrats to your DS!
Second, in regards to AP tests/placement/skipping college sequences–we have been closely considering this as my D has taken AP Physics 1 and AP Calc BC. It is a bit more complicated for her though being an aspiring physician as it seems many med schools do not favorably view retake of any classes in which students have already received AP credit. My D feels very good about calc (having taken the BC class this year in the manner described by @homerdog a page back) and feels that placing out of calc and going on to stats would be best for her with her current career path. (Most med schools only require through Calc 2 and stats for admission).
Physics however is another story. Thankfully she needs a 5 to place out at Binghamton University (where she is happily committed 
and she is pretty sure that this did not happen. So she expects to be retaking physics in college which she agrees is for the best.
Just wanted to alert those considering med school to research about the effect of retaking classes in college if you have already been granted AP credit. I know I was not aware of this before this year.