Professorial style at UCLA is quite varied; it really depends on the particular professor you have. Some are hard core cold-callers; others wait for volunteers; I had one professor who just called on people in alphabetical order. Most of them prefer the Socratic method, but also take time to lecture on points that are particularly esoteric or complicated. Whatever their style, they are some of the friendliest, genuinely caring teachers I have ever had. They always encourage e-mails, office visits, and questions if you don't understand the material. And they also take the time to interact on a personal level; I've had many professors take groups of students out to lunch or dinner, and several have even hosted end-of-the-semester parties at their homes. There are even 1-unit courses called "Perspectives" classes that some professors teach; these courses are meant to be a low-stress (there are no papers or tests), small (10 students), fun (the topics range from the TV show "The Wire" to Comic Books) means of engaging professors in a more relaxed setting.
Student body wise, there is little competitiveness amongst UCLA students. The records office doesn't release your class rank (EVER), so while there is still a forced curve, not knowing your rank takes away a lot of the pressure. Students eagerly share notes from class with those who missed. Nobody hides books in the library; in fact, people actually mark off the section in the books their classmates will need that contains the answer to the problem.