Not hard at all - it’s generally easy to change majors, declare major(s) and take whichever courses you like (as long as you have the prereqs or permission of the prof). Even with the more unit-heavy majors many students still find time to explore other areas.
Don’t fully agree with this - many students “draw” (go through the lottery) in groups with their friends so that they can live together. You can choose to remain together as a group if that’s what you prefer. You can also stay in the same dorm if you pre-assign or if it’s not a more competitive dorm to live in (or not an all-frosh etc dorm).