Housing: learn early not to trust everything that the school tells you.
One piece of particularly bad advice you will get all throughout your first semester is that you should focus on finals and that you have just as good of a shot at getting a firm job if you wait and apply after finals are finished. This is a blatant lie.
Social life: For me, a major step down from my undergraduate institution. (But then again, I don't think Berkeley has ever held the dubious honor of being the #1 party school in the nation.) There are often kegs in the law school courtyard in the afternoon, and there's one major social event in the fall (Berkeley Law Foundation Benefit Auction) and one in the spring (Barrister's Ball). Clubs hold quasi-social events now and then. Firms have wine and cheese parties on campus fairly frequently, so there's plenty of opportunity to network early on.
In terms of events unrelated to school, Berkeley seems a pretty dead place. With the exception of a few VERY mediocre bars, the entire town shuts down at 9 pm. If you want to go to a club, your best bet is the city. That really goes for anything even remotely resembling fun and entertainment. And even for that, SF is fairly deficient.
The good news is that during 1L, you probably won't have much time to worry about that stuff. So look on the bright side of things and work on your pick-up lines at Cafe Zeb.