I do not recall there being a lot of physics in the physical sciences section but it has been a long time since I took it. I do not think you will be at a severe disadvantage. When you are preparing for your MCAT, perhaps focus more on the physical sciences and do some practice tests. You will get a better sense of what you will need to work on. Good luck.
If you are thinking of pursuing medicine, I suppose studying anatomy early has some minor benefits but the truth is you will have so much exposure to anatomy that taking it this early on probably will not make much difference in the long run besides satisfying your interest.
Physics, if it is required later on in college, could be a good investment, especially if it is a pre-requisite for some more advanced classes. Unless you are thinking of going into something along the lines of an engineering or physics domain, I think that physics is not particularly useful. While it is part of the physical sciences, which is a testable subject on the MCAT, it has very little bearing practically in medicine. There is a lot more biology, chemistry, biochemistry, and physiology.
Honestly I cannot say I have used it a lot. Organic chemistry comes into play a bit when discussing things like pharmacology and understanding how drugs work but it certainly is not to the same depth of knowledge that is taught in straight organic chemistry. Biochemistry however does play a significant role when dealing with things like endocrinology and metabolism. Physics and calculus are not heavily emphasized.