What kind of physics subjects are there in total?

Not many schools offer an engineering physics or astrophysics major, but they exist. Other than that, you'd just major in physics. You'd take classes in a lot of different physics fields, but your major, and even the PhD if you want to go for one, would just say 'physics'. The fields you can specialize in include astrophysics, biophysics, geophysics, particle physics, nuclear physics, optics, electronics, quantum mechanics, classical mechanics, modern physics, materials science, bioinformatics, condensed matter, electromagnetism, thermal physics, statistical physics, computational physics, and probably more I'm forgetting right now. No, you don't start your major in high school. You start it when you get to college.

Electromagnetism and Circuits

Intro to Physics.

You apply for a major at a college/university while you are in senior year of highschool (December usually). They choose to accept or reject you.

If they accept you, you go to the college and they make you take the courses for that major. These will be the basic courses. Calc, Chemistry, Physics, English, General Electives, Intro to Engineering.

Then in the end of Sophmore year in college, if your GPA meets the minimum requirement for the major, you get accepted into the major. Junior year is the first year in college where you are officially in a major.

Yeah My brother is going to take Physical Engineering.

He has this passion, I haven't a clue what that is about. LOL.

chemical physics, bio physics