These are all solved by Vanced. Paying for Youtube premium does not solve any of these.
How badly Mozilla messed up with Firefox on Android is worth another topic, however.
[0] https://addons.mozilla.org/it/android/addon/video-background...
Background playback is a paid feature. You may disagree with that decision but the option is there if you wanted it.
All of those above are possible via the website - it remembers your video's quality and speed preferences.
There are too many youtube stories shoved right in your face with the app - no way to disable it.
There is no way to disable the 'cast' button from the player - it's not very useful but you can easily fat finger it.
That's just the surface - i haven't even gotten to the ads, and the forced community posts etc.
No background play
Mainly
I can modify my behaviour instead. Watch using computers with Adblock and de program myself to want to listen to music from YouTube.
Boom done, no need for a YouTube subscription. Subscription hell has got to end.