................do people going to med school need to take calculus? Where does it tie in with a medical career?

Most med schools will require math through calculus. You might not work with a lot of calculus problems as a doctor but it's going to make you more well-rounded. In my opinion make sure you have an advanced biostatistics class, it will be much more useful to you.

So should you take calculus in highschool or wait until college?

When I applied Harvard was the only school that required Calculus, the others only required 6 credits of college level math. I think you need to take it in college as only those credits will count for pre-requisite courses. Good luck