Freshman Placement Exams at Cornell

Hi everyone, I just got accepted to Cornell. And I am planning on doing the Math/Phy double major plus the CS major/minor, not sure about the CS though. Granted, I know it’s gonna be tough, but I’m fully committed to applying every bit of effort in to my studies. I learned in an international curriculum so I have no AP credits or otherwise to count towards college. I’m thinking of taking the Placement Exams to get some of the easier stuff out of the way. How tough are the Placement Exams? (esp. the Phy/Math/CS) And how can one prepare for those? (Books to study…et cetera, s/o told me Serway College Physics and Thomas Calc)
Any other advice on how to lessen the course load?

p.s. I have already finished my classes, so I have nothing (academically speaking) to do until August.