String theory and loop theory should eventually answer these questions.
String theory suggests that all forces materialize when the unified field in many dimensions (26? or at least 11 for superstring theory) separates into first the gravitational and GUT forces or fields during compactification of 16 of the 26 dimensions. The GUT field then separates into the strong nuclear force and the electro-weak force during formation of matter and the subsequent compactification of 6 of the remaining 10 dimensions to obtain our 4-D space-time. The electro-weak forces subsequently separates into the EM field and the weak nuclear force at a relatively low temperature (compared to the big bang temperatures).
At roughly that same low temperature, the Higgs particle transforms its energy into the mass of ordinary matter. One thing I do not understand is how the gravitational field can exist before mass is created by the Higgs particle. Perhaps the universe has mass from the strings higher vibrations which die off at low temperatures where the Higgs mechanism takes over.
Gravity had to exist at the moment of the big bang for the gravitational energy is negative and the particle velocity energy is positive, the total energy adding up to zero, which is how the universe can be created out of nothing. The unified field has no mass or matter. It's pure force. It is not clear if it even contains energy, for most of the energy in the big bang comes from the negative energy of the gravitational field of the matter that forms in 10 dimensions.
You recall that superstring theory is really 11 dimensional. Well current theory by Witten and Duff indicate that during matter formation, two separate 10-D worlds form connected by the compactified 11th dimension- the connection is in the form of strings from one world to the other connecting physical matter with matter (axions?) in the other world.
Hence, string theory suggests the possible existence of physical and heavenly worlds. A supposition is that dark matter inhabites the other world.
Loop theory tries to do the same thing without postulating space-time and deriving the dimensions.