Limited to a selection of pre-approved extensions (Ublock Origin is included in said list); however, you can get around this by using Firefox Nightly and enabling developer settings, which allows you to add a custom list of extensions, which can include any extension for desktop Firefox, including things like SponsorBlock. (Credits to https://lemmy.world/u/Pr0phet )
Depends, usually yes, just check out what the updated Manager says is the latest supported YouTube version and if it's newer than what you have then yes, you'll have to download it
So I ITed the hell out of it. I uninstalled and reinstalled it, and now it's working again.
No idea why that worked or what the problem was. Although I have noticed that apps installed via f-droid are hit and miss when it comes to updating correctly, so perhaps it tried to update and got stuck?