Some do, most don't. Lecture classes are too big for professors to get to know you, unless you go to office hours frequently. There are smaller classes you can take, or seminars, and recitation classes for lectures are smaller than the lectures, so it is possible to get to know some instructors well.
My favorite class this semester is my writing class. There are fifteen of us in the class and we meet twice a week. Every class, three or four students read whatever essay they've written for the week and then we critique them. It's a really good class and I feel like I'm learning a lot.
My least favorite class is 8.02, Physics II. It should have Calc II as a pre-req, but since that would put a lot of people behind in majors requirements (what with prereq and coreqs and all that), it's a coreq. So a lot of the math we have to do in 8.02, I haven't learned yet.
Students study a LOT. Sunday through Thursday, basically I go back to my dorm after classes end and start doing work, and work until 2 or 3am, stopping only for dinner and short study breaks.
Class participation depends on the class. In my writing class, for example, there is a lot of participation due to the class size. In my calc class though, since it's a lecture, there is very little participation, but we have recitation twice a week that gives us more of a chance to speak up and ask questions. Physics has a lot of participation because of TEAL (Technology Enhanced Active Learning), the purpose of which is to create more participation.
MIT students have conversations about everything outside of class, and intellectual conversations are definitely part of that. Last semester, some friends and I were talking about which is more socially accepted, rape or murder.
Students are definitely not as competitive as in high school. There is a lot of collaboration and interest in helping your classmates succeed.
The Electric Engineering and Computer Science Department (Course 6) is the biggest, and arguably the hardest, department at MIT. Almost a quarter of students are Course 6 majors, and even students who aren't frequently take Course 6 classes. There are 3 possible majors in 6, 6-1 (just EE), 6-2 (EECS) and 6-3 (just CS). The curriculum for Course 6 was changed over the summer in 2007, so a lot of the traditional Course 6 classes have been revamped or even cut out completely.
Some of the GIR's (General Institute Requirements) I think are a little ridiculous. I understand that they want us to be well rounded and all that, but Course 6 majors taking Chemistry or Bio, just doesn't have any purpose.