Ive read that dark matter is making the universe expand faster than usual. How is that even possible?
They say that dark energy is causing the universe to expand faster. The dark energy is from empty space, and the more the Universe expands the more empty space there is, so there is positive feedback and one would expect instability.
Dark matter is not dark energy.
In terms of gravity and the expansion, dark matter acts like regular matter, and pulls things together.
For dark energy, see the post above.