I've had quite a few large classes, but I've also had some great professors that I have been able to interact with and who are VERY helpful, some of which I still talk to occasionally and who would remember me even though I took their classes last semester.
My favorite class is my History of Rock and Roll II class, by far. I am a music studies minor, and the class is excellent. It focuses on the music of the '60s and the professor is the greatest man to listen to. He is so knowledgable! I am sure, though, that once I take the Music of the Beatles class, that will be my favorite (and it is also taught by the same man, Glen Gass). My least favorite was Finite Math for the Sociological and Biological Sciences (A118) with Prof. Wheeler. Horrible requirement to fulfill, horrible class to sit through, waste of time, I didn't learn much of anything that is applicable to everyday life.
I've met quite a few students who do the bare minimum of work, and then I've met quite a few who study MUCH more than anybody should (I DO live on an Honors floor, so this happens a lot). But go to the Library and it's always full of kids hitting the books.
Class participation is much more common in smaller classes or upper level classes. It really depends on the teacher and how much they WANT you to participate.
I have had some very interesting intellectual conversations outside of class, mostly with the people I live with. It really depends on the type of people you talk to.
I haven't noticed much competitiveness yet, but I am a journalism major, so I might see it in the next few years (although they don't seem TOO intimidating so far). I think you'll find it more in the science majors and ESPECIALLY the business majors--they think they're gods.
I would say that my History of Rock and Roll has by far been the most unique. IU was the first college in the nation to have classes like this, and we are lucky for it, although there are many other classes that might surprise you--we have a class about chocolate and one about beer, and I'm also taking one called "Elvis, Dylan, and Postwar America" that's great, too.
I haven't gotten too heavily involved in my journalism major yet (although I was a direct admit), but I know that IU is known for its great J-school. The Honors program is tough to get into and I've talked to a few people that say it's too limited in its acceptance, but you'll have that. Also, it's focus is definitely on newspaper and PR, and other aspects like magazines, broadcast, and online media don't get as much attention as they should. My profs. have been wonderful so far, though, so no complaints, although the requirements for the major are a bit much, such as required Economics and Statistics, which for a person like me (I'd like to be a magazine editor) is a bit pointless.
I have talked one on one with a professor or two outside of class, and I am actually studying abroad with a few other students with my History of Rock and Roll teacher in May.
The requirements aren't too bad, although I feel the math/science requirements should be dependent on your major.
I feel that in certain departments it is very much geared toward getting a job (like pre-Med and Business), but others are very open and let you take what you want from them.