Well, look at it this way...
If there wasn't any black holes (or if black holes didn't have a massive gravitational pull), life as we know it probably wouldn't exist.
Answer
Even though black holes suck through parts of the universe, the universe is inevitably big, and growing so as the universe is being sucked into another dimension by black holes, it is also expanding.
Probably stellar mass black holes
No.
The density of matter just after the big bang is calculated to be sufficient to have spontaneously created black holes; such are called primordial black holes, and searches for their existence are ongoing.
Black Holes.
Answer
There are already black holes within the universe
Even though black holes suck through parts of the universe, the universe is inevitably big, and growing so as the universe is being sucked into another dimension by black holes, it is also expanding.
Black Holes' can 'eat' any type of matter in the Universe.
Probably stellar mass black holes
The universe likely contains millions upon millions of black holes.
No.
Yes.
The black holes may not devour everything since the outward velocity of the matter in the universe may escapethe gravitational pull of the black holes. Stephen Hawkins reckons that even the mass in the black holes would diminish over time, though over trillions and trillions of years.
Primordial black holes are theoretical black holes that could have formed in the early universe. They are thought to be small and have a wide range of masses. If they exist, they could have implications for dark matter, gravitational waves, and the evolution of the universe.
No.