I am favorably impressed by your essay. I think you raise a number of interesting points. Your postulate #4 is though something I think that needs further examination. This is in particular with respect to black holes and event horizons. This is not to say that I think it is false. It might have some greater generalization though with respect to black holes and quantum gravity. My essay It From Bit is Undecidable discusses a possible algebraic structure of the vacuum plus event horizon underlying quantum field theory. At any rate you might notice your essay score just went up.
I too think the Higgs field is connected to spacetime. One could consider this with respect to accelerated reference frames. Quantum field interactions have in the standard Feynman diagram approach pointlike vertices. These are not Lorentz invariant, which is something string theory fixes. However, without going into string theory per se we can consider these vertices as regions of large acceleration. On the Rindler frame of the particle there is then an Unruh radiation. The temperature associated with that physics can induce phase changes. The Higgs field may then be an epiphenomenon of spacetime physics.
This might also be considered with respect to inertia. Inertia is really Newton's second law. Inertia is just the property of a mass to accelerate with a changing spatial velocity. A massless particle can accelerate, but it its spatial velocity still remains the same, v = c. A massless particle can be confined in a region so that its tangent velocity in spacetime remains on a light cone. The picture attached illustrates this. In this case the particle is executing zitterbewegung. This is due to the interaction with the Higgs field that keeps the particle in a confined region. The zig-zag diagram on the left illustrates in two dimensions by the interaction of the Higgs field at the vertices. In this picture what we call inertia is a bit of an illusion. The diagram on the right shows a massless particle kept on a spiral path in spacetime, which gives the appearance on a large scale of a massive particle. The motion of this massive particle due to a force amounts to a deformation of this "tube" so that the actual particle is always on a path tangential to a light cone.
Spacetime is locally or that is flat is given by the Lorentz group, which is SL(2,C). The light cone is a projective subspace PSL(2,C). The actual path that particles take is then on this subspace, even in the case of massive particles. There is a short exact topological sequence that relates SL(2,C) and PSL(2,C), and the physics behind this involves the Higgs field. In the case of self-confinement of gluons this is determined by QCD. There is then I think a relationship between the Higgs field and weak interactions with spacetime. Remember the Higgs field couples through the weak isospin charge. Similarly with QCD two gluons in an entanglement (or bound state) that is color neutral is equivalent to a graviton; they both have the same quantum numbers. There is then I think some deep relationships between gauge fields and spacetime that currently are not understood or even explored.
Lawrence B. CrowellAttachment #1: 1_zitterbewegung.JPG