Calculus-Based Physics During Summer?

If your school offers it, go for it. Electricity and Magnetism shouldn't be that hard, after all, it's only a 100-level course, at least at most schools it is. I'm surprised your school offers Dynamics and Mechanics of Materials in the summer--I wish I had that option! But if you feel you can handle the course load, go for it. If you can tackle Statics, Dynamics, Calculus, then E&M should be cake--don't sweat it, it's just a freshman level physics course. My only question is if you can take Dynamics concurrent with Mechanics of Materials--some places have Dynamics as a prerequisite--I'd check on that first.

It's almost split this way, though--either you like the mechanics and kinematics side of physics, or you favor electricity and magnetism. It's pretty much why some people are aces at Mechanical Engineering but bottom out in their E&M physics class and their "shocks for jocks" EE for non-EE majors class, and why some folks are aces at Electrical Engineering but dreaded their kinematics/mechanics portion of physics and stay away from ME courses like the plague. So I wouldn't sweat it if you take E&M and find it not as pleasant--just pass the course so you can take the next course needing it as a prerequisite. But judging by how you feel about the other courses you've taken, E&M should be cake. You'll be fine.

Also to note--most schools actually function on semesters nowadays. Quarters are disappearing as more schools switch to semesters. Been through quarters, hated it, semesters just make more sense.