Most classes at C of C are pretty small--20-30 people. The intros or very popular majors may have 70 people lectures but I've only had one that big so far. C of C does have gen ed requirements that can be burdensome, especially if you have an intense major. The HC has a fairly heavy load, too. But AP credit does count for lots of classes and has helped me out immensely, especially for satisfying requirements for classes that are outside my major/interests. Since I'm in the HC there are extra requirements like Western Civilization (12 hour course), special topics, math requirements, science requirements, but I've finished in my sophomore year. I personally like the variety required because it shows students disciplines they might not otherwise have gone into.
I'm in the anthropology department, which is pretty small but I love all the classes I've taken and my professors. It's like a family because the students all have the similar interests, we see each other all the time, and the professors are very supportive, accessible, and helpful outside-of-the-classroom. They're always willing to talk about internships, grad school, their research, etc. during their office hours. My department will offer classes catered to students' and professors' interest and I've seen other smaller departments (even bigger ones like English) do that as well. I've taken medical and ecological anthropology which were fascinating courses. The HC college and some of the "minor" departments have really interesting special topics courses.
Other big majors may have some trouble connecting with their departments; I'm not sure. The biology and chemistry departments are huge but excellent. We have a top-notch chemistry program, and obviously our marine and ecological program is very good if slightly small. A large number of students are pre-med, which is a demanding major in terms of time spent on homework and effort put forth. Intro classes for pre-med and also English are weed-out courses; they require lots of work. My friends have to work in the English department but if it's your passion you will do well because there are excellent professors. Other big programs are the business and communications majors, which are considered the "joke" majors or the ones that not very serious academics end up in. But both programs are very good, especially business with all of the tourism and hospitality connections, for a passionate student. Art is another big discipline, whether studio, theater/music/dance, historical preservation and art history. The theater department likes to be edgy in terms of gender roles, but I've enjoyed all the performances I've seen so far.
The smaller departments like WGS, Jewish studies and other cultural minors, the more obscure languages (Hindi, Russian, Chinese) are growing and gaining more interest from students. Spanish is the big language major.
A lot of people take classes with the physical education department. Electives like sailing, yoga, and dance are very popular and fill up quickly because they utilizes the water or the beautiful scenery.
As for studying it depends almost entirely on your major. I have to work a fair amount, not for anthropology so much as HC and pre-med requirements. Class participation also depends on your major. The humanities and social sciences are definitely geared towards class discussion and interaction. Not so much in science or math as far I've seen.