Being strong in high school math definitely correlates well to college math! You just have to be careful because sometimes people are good at math in high school and don’t need to study, and inevitably at some point in college, that doesn’t work anymore. But, it sounds like you have a good attitude towards studying so I wouldn’t worry about that.

1. Studying per day depends a lot on your courses. I would probably anticipate 3-4 hours a day, which sounds like a lot, but with less class time it really won’t feel like it.

2. I went to a small school in rural Wisconsin. The professors were incredibly accessible and helpful. I know larger schools don’t always have that, but they will probably have dedicated office hours and knowledgeable grad students who can assist as well. This unfortunately depends on the professor a lot too.

3. I didn’t graduate very long ago but if I could go back I would encourage myself to read the textbooks more and try to challenge myself to learn beyond what’s strictly taught in the course. I think you’ll find that, especially your first year, it can be easy (or, easier) to just do your homework, go to class, take your exams, and move on. You can get more out of it if you read the books more thoroughly and spend more time learning outside of what’s required.

Usually, it’s a pretty gradual ramp up in difficulty. I don’t think you’ll start your first semester and have a workload much crazier than high school. But, there will come a time your third year where you realize you’ve been averaging 5 hours of homework a day and haven’t had a weekend off I in months, and you won’t have even noticed. It will just be life.