Dark matter should be considered a gravitational object without temperature as it does not interact with ordinary matter. Yet under the immense gravity of dark matter it might be possible for ordinary matter to have risen from this pressure. The pressure then might push back leading to dark matter having a high temperature. This leading to the origin of dark matter to be “cold” and showing the first sign of temperature… a hydrogen atom or proton. Dark matter may not have its speed limit set to the speed of light. It might be able to move faster. Falling dark matter from the outer edge of the universe could easily reach over light speed in the time it takes to fall to the largest source of gravity. A simple equation I can’t figure out. I know I didn’t answer all your questions but I believe that is the just of it.