I've only ever been using "regular" dash, a minus, for that. How do you even type yours? If I ever needed differently-sized dashes (and I don't know the difference between them) I always used wiki to copy them.
(disclaimer: I feel like this obsession with dashes is special to native English speakers, which I'm obviously not)
Only a small subset of native english speakers. Most don't use dashes at all, of those that do most just use minus for everything, some exceedingly small group cares about typographical details and thus distinguishes the different sorts of dashes.
It's an attention to detail thing that you'd definitely want to get right in a physical textbook or the like.
Depends on your OS. Mac is the easiest, it's just ---, Linux depends on your distro, if it uses KDE, it's <right-win>--- —. Windows is a little awkward, I think you need <right win>+the code point.
It’s an obsession with literature and/or typography nerds specifically.
Option-shift-hyphen types an em-dash, option-hyphen an en-dash. You can also hold the hyphen key (on a Mac or iPhone) and it will allow you to select either. Em dashes are used—like—this—as something spiritually akin to a parenthetical. En-dashes are used within ranges: Feb 14–17.
silly specific: the minus sign is a separate character. The dash equivalent is the en dash (–), versus the larger em (—) and smaller hyphen (-).
The en dash is also used in things like scores (3–2 Turkey), votes (the bill passed 58–42), or connecting words where the second part is longer than one word (the Australia–New Zealand alliance.) You can remember the latter as, "a hyphen isn't big and strong enough to hold on to more than one word.
If you're on a mac, pressing Option+- is the en dash and Option+Shift+- is the em dash.