Are you talking about these containers?
Each container is isolated from the others. If you don’t want a tab to track you, just use a dedicated container for it.
You can also configure Firefox to always use a dedicated container for certain domains.
As for destroying the data, you probably just need to clear cookies on close. That’s configurable. If you are extra paranoid you can also clear the cache.
Did I miss something?









I don’t think you need a guide. Just install the extension and give it a try. It’s pretty simple and intuitive.
It might be possible now, you could give it a try. But anyways, I don’t see how changing the default container for new tabs could be useful. There is a default container which is the “no container”, why would you want to change it?
EDIT: yes, it is possible now.