For us in Europe, used to buying 3rd party books (or paying $1000 for the ATPL manuals) the amazing thing is that the FAA publish free pilot knowledge books that are of a high quality, up to date with modern methods and very well illustrated. They are an excellent complement to the regulatory publications.
Take a look at
Pilot's Handbook of Aeronautical Knowledge
Chapter 1 gives a good overview of the FAA system
Chapters 12-14 are probably what you need to read, plus there is some info on charts and flight planning in Ch 15. The "Cover-Preface" section has the detailed contents.
The full list of books is here:
Aviation Handbooks & Manuals