Astronomers believe that black holes exist in the center of every universe. They even think that there may be a black hole in the center of our galaxy, the Milky Way
No. Since the black hole is a part of the universe it would be physically and logically impossible to suck itself into itself.
Well, a singularity is part of a black hole. Although no-one really knows what existed before, a likely explanation is that every black hole contains another universe. So when our black hole was created, we were too.
The universe is expanding but I'm not too sure about the second part. The obvious thing is that a black hole looks like a big black hole.
There are already black holes within the universe
a black hole sport, a black hole.
Perhaps you are confusing Universe with galaxy. Most galaxies have a black hole in their center. The Universe has no such thing as a center.
No, the universe is mostly a vacuum but a black hole is (theoretically) when gravity goes wild and rips a hole in space and time
Well if it DOES happen and a black hole DOES destroy the Universe, then we won't be around to worry about it.
Unlikely. The universe is a very big place, even next to the largest black holes we know. For a black hole to suck in the entire Universe, it would need to be nearly as massive as the universe itself. There is no way that such a black hole could form.
It is unlikely that any single black hole will ever consume even a significant part of the matter of the universe. However, the Heat Death hypothesis does allow for a large portion of the matter in the universe eventually falling into multiple black holes, and for black holes merging to form more massive black holes, possibly massing many times the Galaxy's central black hole.
The universe likely contains millions upon millions of black holes.
It is a possibility that the Universe resulted from a black hole, and that black holes in our own Universe result in new universes. But all this is extremely speculative.