I graduated from a UCSD, and I can really only speak on my experience but I loved my undergrad. The professors truly care about you passing, especially if you go to office hours constantly. Plus, going to office hours will definitely boost your chances of getting LORs. In regards to opportunities, it’s what you make of it. You can totally join a pre-med society on campus that guides you to LOADS of opportunities. Plus, the pre-health advisors are for life, which a lot of people don’t know. So even after you graduate, you can still get pre-health advising.
In regards to GPA and curving, it depends on the professor. Each prof and department is different and I think that speaks for any University you apply to. However, UCSD science courses are tough but they definitely prepare you! For example, one bio prof I took had questions from previous MCAT exams on his midterm and final. UC campuses want you to succeed but that doesn’t mean they wont challenge you, especially if you plan on applying to medical school.
Hope this helps!