Answers in order followed by some discussion

1. Out the gate you don't need to teach them anything. As they encounter things that require rules, you inform them of them. So when they first want to try scaling a wall you inform them of how skill checks work and have them roll. You introduce the rules of combat piece by piece. Just ask them what they want to do IC and explain how it can be accomplished.

2)Again you don't need to teach any, but I find 5 minutes of talking or a half a page of writing is a good primer. The 2 best ways to handle this are have them play characters who would be of similar ignorance(ala in World of Darkness people new to the supernatural, or in D&D, foreigners to the country they are adventuring in) or simply have them roll intelligence type checks anytime they do something that doesn't fit and based on the roll explain to them why that might not be a good idea. Still let them do it if they want. Also offer them lore checks very frequently.

3)I'd say make characters for them. You can do this either by discussing a general idea of what they want to play or just make a bunch of premades and hand them out. Let them adjust stats at will as they learn the rules, but start by doing all the work yourself. You'll probably enjoy it more and it makes it much easier to get them invested.

Alright, discussion time. When first introducing new players to a game, I personally prefer doing a one-shot: a self contained game and story that is much more rail-roady than normal, is meant to finish in a single session, has pre-made characters and is designed to highlight a few of the main aspect of the game and will deliberately avoid some of the more complex stuff. This will allow them to get a sense of how the game is played without having to learn all the rules or spend much time checking rulebooks. It also keeps the game more focused than a typical campaign session which sometimes can become just messing around with people at the tavern.

It is always possible to turn a one-shot into a campaign if people like their characters or if they like the rules, but want to switch things up, abandoning it all now that they have some idea isn't that hard. You can of course let some players keep characters while others make new ones in either type. It also allows you to jump to a different game if people aren't that interested without wasting all that time building a campaign.

When designing my one shot, I try to create characters that will have all the major archtypes of the game/setting. In addition I try to come up with 2-3 different types of encounters that explore different mechanical aspects so players get a sense of all of them. I usually put in 6ish total encounters, 5 fairly short and easy, 1 hard boss one, essentially like a tutorial mission at the beginning of a video game. I make sure there are some elements that I actively don't include and will have no way of showing up if it's a complex game like WoD or D&D, because that can bog down the game. When showing it off it's best if things keep moving quickly.

Final point. I almost never introduce a game as complex as D&D or WoD without someone else in the group having at least a passing familiarity with the game, or everyone having experience in multiple systems so picking up a new game is fairly easy for them. I don't know much about the other two but they looked a bit more complex than I think is good to start with. If your freinds are completely new to RPG's I'd recommend something like Dungeon World, Fate Acclerated, or Savage Worlds to start, and then move on to one of those once they have the basics of how RPG's work.