Get permission before posting anything. You obtain permission from the music publishers.
If you have advertising enabled, by arrangement the copyright owner will get a large share of YouTube adverttising income.
Much of the advice you will get will be USA centric... ie obtain mechanical licenses from Harry Fox Agency. Even the advice you have above is USA centric, ie go to the US Library of Congress and ask. No doubt that the USA is the largest market, but you will want to make sure you conform with the legislation in a variety of jurisdictions... otherwise you might find yourself in breach and sanctioned by YouTube... or at best not streamed in countries like the UK, Australia, New Zealand etc.
Are you a member of a PRO? They should also offer advice. For a start they have agreements withe PROs in all countries and will collect nd distribute income from broadcasters to members and PROs in other juridictions.
In essence, some copyright owners are completely OK with YouTube covers. They generally promote the song and the original artist. Others most definitely do not like YouTube covers and will pursue YouTubers. Sometimes you can negotiate a deal post-complaint, but if you fail to negotiate, any video removal will count as a "strike" against your YouTube channel.
Something important to know...
Cover song videos are NOT protected by a mechanical license.
For your own works you can register an ISRC code so that advertisements will automatically pay you if your work is ued in a mashup or as a video soundtrack, or a fan lyrics video.( @fasstrack I meant to mention this to you. Do this via the YouTube Content ID system... which is simply a registered ISRC code. If you don't have ISRC code generation because you are not registered, you can get one via CD Baby or Reverbnation.)
To distribute and sell your own audio of a cover song, you have to have a mechanical license from the publisher of the song, and pay them the appropriate mechanical royalties.
But I repeat, that does not license the VIDEO fro your song.
Commonly YouTubers are not having videos removed, and not suing YouTubers for breach of copyright because of YouTube's monetization scheme.
That said, it is worth noting that copyright owners are suiing some YouTubers, and when they do, they are winning.
To stay legal you need a Sync (synchronization) license as well as the mechanical license. The sync license determines how the song can be used and the financial compensation for that use.
It all comes down to the negotiation with the publisher.... and how reasonable the publisher will be... and that can massively vary.
And that is a lot of hassle....
So often going the Content ID route is much better and perfectly serviceable for most artists.
Content ID gives music publishers the ability to:
Block videos - you don't show up in search
Restrict viewing according to territory/country
Mute your video — so video plays but no audio
Block specific platforms — so no video on mobile, or websites etc.
The only negative here is that you have recorded the song and now cannot use it. On a bright note, at least you are not being sued and being banned!