Calculus will help but there is more to physics than just that.
Calculus; by a long shot.
That should probably be easy. Try it out to be sure.
Calculus was invented to solve physics problems, so the importance of studying calculus is to solve physics problems.
There are always other problems harder than what is called "calculus III" But what is learnt in calculus III is just basically the "stepping stone" for what is needed for more advanced math in later subjects, such as theoretical physics, protein folding, etc... For me, I determined that Calculus II was the hardest calculus course, then Calculus I, then Calculus III being the easiest. After that... there is linear algebra.... and don't let its name fool you just by having the word "algebra" in it... it is pretty much a HUMONGOUS pain in the buttocks
The purpose of calculus is to solve physics problems.
Definitely AP Algebra (1)^2.
Opinion: Calculus is much harder, mostly because of it's complexity. Calculus requires much more formula memorization and ingenuity.
Calculus is much harder than statistics, and don't really have anything in common other than algebraic process. Calculus is the study of rates, while statistics is probability.
Calculus was created to prove physics which defines the laws of nature.