Hello,
1. For math I would suggest not taking calculus 2 at all. Most medical schools only need 6 credit hours of math as a prerequisite. If you passed the AP calculus AB test, then you should have 3-4 credit hours of math under your belt already. I suggest taking statistics. Honestly, there is just no need for any tougher math classes outside of calc I and stats.
2. BME and Biochem are two of the hardest science majors at my school, and students in these programs do have lower GPAs. If you are gunning for medical school, I suggest not doing BME. There's absolutely no need for you to take those hard major specific BME classes and risk a lower GPA.
3. As for EC's, I suggest joining all the pre-med/pre-medicine clubs/honor societies, and try and go for a leadership position in these clubs later down the line in your undergraduate career. Start at a clinical volunteering site as well as a non-clinical volunteering site as early as possible, and stay consistent with these throughout your undergraduate career; medical schools love commitment. Other than that, just join whatever clubs interest you.
Good luck in college.