Is this a good place to start learning Linux at a finer level?

Sure but take it with a grain of salt, it’s from 2009. (Disclaimer: I didn’t read the whole thing, but patterns probably haven’t changed completely since then) Kernel.org has documentation, that should be the go-to. Try to setup a test-environment with minimal kernel, read the source code where it interests you and hack around a bit.

Is a CS degree kind of required for that kind of thing?

No, just knowledge of C, operating systems and a bit of how your hardware works, or the desire to learn all of those. I know people with CS degrees that have no clue, I know people without a degree that submit patches. But it probably won’t hurt, unless you get some bullshit business-focused degree.