The functions described in the article are crucial. You should rewire your brain to type them every time you ask yourself a question.
Generally speaking, Unix is very good at self documenting. Whether it's text editors (vim/emacs), shells (bash, zsh, ksh) or just plain man pages (did I mention the info pages for GNU tools?), the systems are great at holding their own full documentations.
I cannot recommend enough adopting the reflex of checking the local documentation before opening your web browser and hitting Google.