I had so many questions when I was in high school.
I think you're getting ahead of yourself, though, so let's take things one step at a time. Also, keep in mind that every university will be different - so my experience will not be representative of everyone else's experiences.
First, figure out what you want to do, or at least what field you would like to get in to. Knowing your desired career will help you decide which university you would like to attend. For example, I majored in psychology, so I wanted to find a university that had plenty of internship opportunities for psychology majors, professors who had published material and were reputable, interesting classes, etc. Figuring out what you would like to do is honestly the most important step, so take your time in exploring all your different career options. If you're interested in recreational therapy, look up some recreational therapists in your local directory and see if you could meet with them for lunch. In exchange for buying them lunch, you can pick their brains - find out what a "typical" day is like, what they had to do to get their jobs (ex. schooling and previous jobs that allowed them to work their way up the occupational ladder), what the average salary for their professional is, etc.
Once you have decided on a career, do some more research and find out which schools offer the best programs. For example, my undergraduate university was one of the top 50 in the nation; however, that didn't mean all of its programs were also in the top 50. They had great theater and biology programs, but many of their other programs were average, or even mediocre! Just because a university is well-known doesn't mean it will necessarily be the best fit for you based on your intended career path.
After you have selected several universities, look at the department websites and find out what the course requirements are. For me, I needed 180 units to graduate, a certain number of which needed to be upper-division psychology courses. I found out that a typical class was 4 units, meaning I could expect to take about 45 classes over the course of 4 years, which breaks down to about 11 classes per academic year. My university was on the quarter schedule, meaning that I had three terms each year (assuming I didn't take the summer quarter), meaning I would have to take 3-4 classes each quarter in order to graduate in 4 years as I had planned.
If you're feeling a bit overwhelmed at the moment, that's okay.
Once you have selected your career and your top universities to apply for, your best option would probably be to go ahead and call the university's department office for your intended program, and asking them to start from the very beginning when it comes to academic requirements (I didn't even know what "units" or "upper-division" classes were when I was in high school!). As I said earlier, it really is going to be different for each university.
As far as housing is concerned, that will also vary for each university. At mine, I was allowed to live in dorm on-campus for the first two years. After that, I had to find an apartment off-campus. Some universities will have housing on-campus, some will have housing off-campus, and some will not offer housing at all (you'll have to find an apartment within commuting distance of the university).