1. OrpheuRegisterHook(). There's multiple tutorials on how Orpheu works and what you can do with it. Pretty much any function from the game is available, but it's not as easy as typing "Ham_Spawn", there's more steps to it. It's a module that is really advanced and requires some knowledge of reverse-engineering and if you are beginner in coding (and it seems like you are), I would advise you to stay away from it for at least some time until you learn more.
As for the rest, you can find all of these in either tutorials or released plugins around the forum, there's so many examples; 2) File reading tutorials; 3) Multiple plugins and snippets with it around; 4) Plugins around here as well as HLSDK; 5) Multiple snippets around I am sure.