Check this out for what is generally expected…also make sure you meet your HS graduation requirements…like you might have to take an Art class, or an Economics class.
http://talk.qa.collegeconfidential.com/high-school-life/2055289-faq-high-school-college-prep-base-curriculum.html
You are correct in that unlike the British System, your AP grades matter more than your AP test scoress. the AP test scores are used to get credit for classes (see your particular college to see how that works).