Martha Said:

How do I boost reading comprehension and speed?

We Answered:

Start reading books. you have to if you want to improve. Start with fun things to read that are below your reading level. That will get your confidence and enthusiasm going. Then move on to something slightly harder. Find a quiet place with no pressures from anyone and try to get some alone time. Once you've finished a page, ask yourself if you understood it.

Cecil Said:

Exactly how much of high school material is actually relevant in University?

We Answered:

No, that's why colleges and universities have English 101 and 102, and Math 99.
When I went to college, I had to have 12 credit hours of science, 3 of math, 12 of English, 3 of computer science, etc, in addition to my major and minor (I double minored). Most students are required to have 2 years of a foreign language, some political science, etc.
So, to answer your initial question, most of your necessary skills were acquired in grade school.