First, USAFA does not have "Plebes." It has 4 degrees/"doolies." (Cadets don't really use the term "Doolie" though.)
Yes, USAFA has a core curriculum. It is 90-some-odd credit hours. Your first year and a half will probably be all core courses. Most 4 digs have 5 academic classes first semester and 6 second semester. After that, it will range from 5-7 for most cadets, depending on their major/minor.