No, we see evidence of dark matter everywhere inside the universe, around galaxies; you may be confusing dark matter with dark energy.
I am almost certainly just talking nonsense, but it seems to me if the light-emitting universe is on one side of a flat plane and dark matter is on the other, the physical distance between the light-emitting universe and dark matter could be 0.
You are indeed talking nonsense.
Yea, total nonsense, the universe isn't 2d, and like I said, see the bullet cluster. Dark matter is here, in our 3d universe, mixed with normal matter.