[a_e_k]

Yep. `C-h k` to look up what a key does, `C-h f` to look up a function, and `C-h v` to look up a variable/setting will get you pretty far.

I'd also add `C-h b` to show you the key bindings. (And `C-h` after a prefix key will usually show you the bindings that start with that prefix.) `C-h a` for apropos to search commands by substring can also be useful.

The thing that makes it really "self documenting" is that these help commands reflect the live environment at the moment you use it. If you've added a new binding in your init.el, `C-h b` and `C-h k` will show it. If you've added a new function in your init.el, or loaded a custom package, all those functions can now be found via `C-h f`. The help system will show you the doc strings for them and provide hyperlinks right to the source.

Moreover, this works for anything that you define on the fly. Open an Emacs lisp buffer, type some elisp code to define a function or variable, execute the definition, and now it'll appear under the above in the help system the next time you invoke help.