Reeve,
The background radiation would be the solution to Olber's paradox. Since redshift is proportional to distance, this is light that has been shifted completely off the visible spectrum. That it is so smooth, at 3.7k, suggests some phase transition at that level. Possibly it is only stable to that level and then starts to shift to other forms of energies. I think gravity is not so much a property of mass, but energy converting to mass and condensing into ever denser forms of matter. They can't find dark matter, but there is an unexplained excess of cosmic rays on the perimeters of galaxies. When mass breaks down and releases energy/radiation, it creates pressure, so possibly the opposite process would create a vacuum. Which goes back to the 3.7k. Possibly that is an initial condensation point of radiation into some primary particle like entity.
Time dilation is due to the fact that since nothing can exceed C and the internal activity of atomic structure, the spin/vibration of electrons, approaches C, if that structure is accelerated to some fraction of the speed of light, the internal activity has to slow, so the combination of velocity and spin doesn't exceed C. So if you have a clock, the rate of atomic activity is affected by velocity and gravity, given the equivalence principle. It's not that the clock in the accelerated frame is traveling a different time vector, but that it has a faster burn rate. It's not traveling into the future faster, but into the past faster, since it ages quicker. This distortion of atomic structure also explains length contraction, since the atom is flattened by the action.
While this effect is apparent for GPS satellites, I think various scenarios put forth, such as time stopping for someone falling into a black hole, are nonsense. Safe to say, if you fell into the core of a galaxy, you would quickly be fried and the ashes scattered. It's a bit like saying that time has stopped for that log I threw on the fire, since it turned to light and light has no internal structure, therefore a clock traveling at the speed of light wouldn't record any change, but time still goes on for me, as I watch the log burn.
In this cycle of expanding energy and contracting mass, I think galaxies are gravitational vortices, not warped space. If they account for all the energy being radiated away, as well as that shot out the poles, it would likely equal all the mass which fell in. It's then radiated for billions of lightyears, until being absorbed by other mass, or finally reaching that degree of being spread so finely and becoming part of the black body radiation of the cosmic background and the cycle starts over.
Some interesting reading;
http://www.americanscientist.org/issues/pub/2007/9/modern-cosmology-science-or-folktale
http://www.fqxi.org/data/forum-attachments/2008CChristov_WaveMotion_45_154_EvolutionWavePackets.pdf
http://phys.org/news/2011-06-physics-einstein.html
http://phys.org/news/2011-12-strange-species-ultra-red-galaxy.html
http://phys.org/news/2011-12-spitzer-hubble-telescopes-rare-galaxy.html
http://phys.org/news/2012-04-fermi-gamma-rays-unearth-clues.html
http://phys.org/news/2012-06-rare-case-gravitational-lensing.html
http://phys.org/news/2011-12-mysterious-red-galaxies.html
http://phys.org/news/2012-07-earliest-spiral-galaxy-discovery.html
There is another topic worth considering and that is the nature of space. Basically physics treats both space and time as measurements, but does measuring space create it? There is a strong tendency to describe it as something, such as the ether, but that doesn't explain inertia. Consider an object so far away from everything as to be in a void. Would it be possible to say it is spinning, without any outside reference? Yet for anything on the surface, spin would create centrifugal force. How could such an effect be due to some outside reference? The only explanation is inertia. That goes back to Zeno's paradox. It overlooks inertia. The only way it would make sense is if for every fractional divide, Achilles and the tortoise both also slow their speed in half. Quite quickly though, they would both be going so slow as to be effectively motionless, as the forward velocity would be less than biological processes, then molecular and then quantum dynamics. Zero has, throughout the course of math and logic, been a poorly considered subject, yet one staring us in the face. We only think in terms of form and motion, not their absence.