Earlier quoted context omitted.
Is all about muscular memory, so you need to repeat and repeat, and take your time to develop it. Is normal not to grasp it after a few hours using the program. Nobody expects taking one karate class and exit being a master of katas. First emacs kata should include this very simple concepts 1.Opening a file (the easy way) -> extra simple. Type "emacs /path/to/my-file" in a terminal. If a file with this name does not…
Yes, except the keystroke to "close a file" is C-x k (for kill buffer). Like you said, muscle memory. It's not surprising that you didn't remember the exact name of the keystroke because normally, you just do it.
(setq confirm-kill-emacs 'y-or-n-p) is one of the most important configs to start with, IMO. Or if you don't want to learn/use elisp, the equivalent Customize setting:
Options > Customize Emacs > Top-Level Customization Groups > Convenience > Confirm Kill Emacs