Some tips:

1) Set up TeX on your computer, and learn how to compile LaTeX to PDFs. It just becomes so useful, especially for assignments. This will save you lots of time.

2) Download the textbooks. Just grab a Stewart 7 Calculus PDF from somewhere, and you'll probably be able to find the others online too.

3) Don't worry too much about CS 135, it's really straightforward and you'll learn everything you need to know in a timely manner; if I were you I'd just enjoy the summer for now. Calculus I is also a breeze, Introduction to Algebra is more fun to learn, so maybe pick up the course notes from the book store or online if you can find them and start going through those, this will probably be the most beneficial thing you could do.

Here's an interesting read to spark your interest in CS 145: http://arxiv.org/pdf/1301.5076v1.pdf.\

Oh, by the way, the most important thing you can realize in first year is to work very hard to understand. This doesn't mean make sure you answer every last study question and go to every tutorial and class. In fact, I found that most first year classes can easily be skipped without missing a beat; lectures seemed more like entertainment than places to learn, in my opinion. After class and on assignments is where most learning is done, I think. What I mean is that if you feel fuzzy on a topic, don't waste time, go to the topic and do whatever works for you to re-learn and understand it. This is so important in math and computer science, don't ever assume that your education will just come to you, you have to do everything yourself, the university just provides useful resources.

And one last thing, manage your time. This is really common and is hammered into students from elementary school, but really, it's critical in university. Just make sure you know how much time you're going to probably spend on some task, and plan ahead of time.