I've personally seen 1,4, and 5.
The 'brilliant' morons are called 'gunners' in law school (though some gunners are genuinely trying to learn something), and they are the worst. They tend to slow class lectures down to a ridiculous crawl that can be unbearable. This tends to be the worst at the beginning and end of the semester.
Drunk people run a real risk of being called on, so they usually just skip that day. Unlike college, every student gets called on at least once in law school, and usually when they least expect it. Some folks get called on a lot more than that. If you show up to class, you have to be prepared for some rigorous explanation. You'll see just how terrifying this can be first week.
Macho dudes fist fighting? Never seen this in law school, though I almost had an argument come to blows (long, stupid story). Cooler heads prevailed. Physical violence can land you a one way ticket out of law school.
I was shocked when I saw students show up wearing pajama pants and flip-flops to class. The profs called them out the first time, embarrassed and humiliated them, and it never happened again.
Some folks just prefer to study in the library (I am not one of them). Some over-study in the library. At my school, the library tends to be empty or insanely full.
Per ABA rules, you must attend at least 75% of your classes to write for the test, so you cannot blow off class too much. It is impossible to never show up and still pass because you won't be allowed to take the final, which can be 100% of your grade.
Interestingly, people do get high in law school but are very careful to pretend they don't. Most students that I found out smoked weed only smoked on weekends after all their work was done or didn't smoke any pot until after finals was over. I knew a few students who smoked whenever they were done with their work for the day and one guy who smoked every night at 10pm because that was his hard ceiling for how late he was willing to work.
I've never seen anyone watching porn in the library (or anywhere else for that matter). Our network blocked anything close to a porn site. I WAS watching Reno 911 (the movie) on my slingbox in an empty classroom once (I was waiting for class to start and had an hour to kill) and when the topless beach scene came on, I was tapped on the shoulder by one of my female classmates, who told me that she thought the movie was hilarious. Embarrassed, I quickly shut it down.