On the political climate: Most of the time, you won’t feel particularly persecuted. Once in a while you’ll see and hear things that will strongly irritate you (safe space protests, anti-Israel protests, Black Lives Matter, and so on), but there’s a relatively strong college republican presence, and you’ll find that there are some conservative tendencies among many of the STEM majors who are too busy with actually putting in the hard work to get a job or go to grad school to participate in political activity. There is an “American Cultures” requirement, which is basically a requirement fulfilled by taking a course that makes you read a bunch of Marx and Engels and teaches how horrible white males are.
On partying: If you’re doing Haas, you’ll probably be partying a lot. Most people are not socially incompetent geeks. Just get used to Cal Football repeatedly breaking your heart.
On Berkeley goggles: Everyone has their own preferences. Visit the campus and you’ll see what I mean.