Second, this statement is questionable: "The explanation is that the wavefunction which describes the superposition of possible quantum states exists at all points simultaneously." This is ONE explanation. It is essentially a non-local hidden variable theory. There are other alternatives, for example that since the intrinsic spinor part of the state vector [wave function] has no spatial or temporal dependence, the collapse of the wave functions along a spin axis involves no space-time communication at all. In other words, it happens in a non space-time dimension, very different from what we ordinarily think of when we think about existence.
Thanks, but to be honest, you write at a level that’s mostly beyond my understanding. I would have to look up and study many of these things to begin to grasp what you are saying. However, given that you spent years in the field, I have no doubt you know what you are talking about. In any case, I’m sure there are others here who understand it better than I. Thanks again. :)