Outside of spacetime = what existed before the bubble of spacetime formed. This is also where vacuum energy leaks in from. This is also where Quarks and Leptons are when we aren’t looking. This is where the waves of particles actually exists and they are all interchangeable. They are the cards in the deck that are the hidden part of quantum mechanics.
The fabric of spacetime = like the atmosphere of the planet surrounds us the fabric of spacetime surrounds the universe. This is where dark matter is which is why we haven't figured out how to see it yet. This is also why dark matter isn't swallowed by black holes. Like the wind told our ancestors that they were surrounded by something they couldn't see, dark matter lets us know it is there. So until we figure out how to see it we just have to rely on a catalogue of it's affects. We will probably harness its power before we actually discover what it is, much like we did with sails and windmills
No it is not and can not be anywhere in the vicinity of mass and matter. Mass and matter excrete static energy.....and possess EM fields that occupy a region of space around the matter. Neutral fields.
Inside any container will exist those fields. And occasionally static emissions.