Don't worry overmuch about the ACT, if you have basic critical thinking skills and understand how to take multiple choice tests, you'll do very well with little trouble. The science portion in particular is a joke -- I got a perfect score on it despite being very much a humanities guy because literally the entire thing is "See this data in the graph/table/whatever? Here is the name of the value we want you to find. Locate that value in the dataset." The multiple guess questions are all set up so that two answers will be blatantly wrong; just eliminate those and if you can't instantly pinpoint the correct option from the two remaining, make your best guess and move on. I took it hungover and with ~4 hours of sleep and walked out with a 32 composite, 'cause it's a fucking joke.
Definitely get on applying for scholarships as soon as you've got your finalized high school transcript, though, because many are heavily favorable for early applicants; some universities even offer a sort of first-come-first-served scholarship just for being accepted.
And yeah, four-man two-bedroom suites are actually (IMO) the best you can get; sharing a bathroom with three others is worlds better than sharing it with a floor, and it means you aren't living alone -- despite what your initial impression might be, living alone is actually a pretty bad thing even for a hardcore introvert (perhaps especially, even) unless the alternative is an absolute shitlord roommate.
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If the state completely covers tuition and books for a big chunk of your time (lucky dog), your main concerns should be with maximizing the cost-efficiency of other things and looking for scholarships for the remaining time; a lot of those will often be department-specific things. After your first semester or two, if you don't have major responsibilities (band, [ugh] Greek life, &c.), consider looking for a job on-campus. They usually won't pay well, but you can end up with an extra $1000-1200 a semester for relatively light hours.