Dear Jim Akerlund,
Thanks for "raising your hand". First of all, to address your "warning sign", although Einstein's presentation of SRT seemed simple enough to start with, as he realised he could base the whole theory on just the light-postulate and the principle of relativity, and thus do away with absolute time, etc., there are significant philosophical issues with the theory that have been subsequently realised---at least for those of us who trust our senses enough to maintain that things must *actually* change. Because the thing is, that the implication of a block universe, in which the dimension of time physically exists as a coordinate of a four-dimensional continuum (which cannot in any way change, because it doesn't *exist* in any temporal sense, time already being a part of the four-dimensional block) is a direct consequence of the simple way that Einstein interpreted the relativity of simultaneity. The fact of this is quite well-known, which is why I dedicated only a paragraph to a number of statements that were made in reference to it, by Minkowski, Einstein, Weyl, and Geroch. In fact, this is what Minkowski's (1908) invention of space-time, as an "absolute world" in which "everywhere and everwhen there is something perceptible", was all about. You mentioned the Andromeda galaxy, and I urge you to re-visit Penrose's discussion of what has been referred to as the "Andromeda paradox", which provides a very clear illustration of the problem. You could also look at the paper by Putnam that I mentioned to Paul Reed above.
Before moving on, I just want to clarify that I believe we live in a three-dimensional Universe, where the Earth truly exists, and where everything has ever happened. But I believe those happenings have only been real in the moments that they occurred, as the arrangement of things in the Universe has continuously changed; e.g., according to this theory, I'm not being born thirty years ago in Saskatoon, because none of that exists any longer, because all that exists exists presently. By this I mean to describe a very Newtonian picture of physical reality, to which SRT is supposed to be opposed. But I don't think that it is, as I think the mathematical theory reconciles very well with such a Newtonian picture, in which photons move at finite velocities through a "present" three-dimensional universe, with the *metrical structure* of the map of events that occur in the special relativistic universe given so that photons travel through it along (invariant) null paths.
Now, I'll repeat the problem: if simultaneity is defined so that the events that occur "simultaneously" in any given inertial reference frame, are those that occur at the same time---i.e., *synchronously*; at the same value of the time-coordinate---according to an inertial observer who remains at rest in that frame, then, because "what simultaneously exists" will be different for all observers, if we integrate over all possible descriptions of "what simultaneously exists" for all possible inertial observers who might be moving relative to one particular observer at one value of their proper time, we find that "what simultaneously exists" actually has to be all of space-time, as a block---so that the best we can say about the perception of change is that "To us believing physicists the distinction between past, present, and future has only the significance of a stubborn illusion", which is something that Einstein wrote in a letter commemorating Michel Besso only weeks before his own death.
Now, (I'm coming to your issue, so please bear with me) I want you to have a look at my Fig. 2. A, B, and C are all inertial (non-accelerating) observers. B and C are moving relative to A, and at rest with respect to each other, with A moving in their proper frames. The figure is supposed to be used to understand how it's possible for only the events that are synchronous---i.e., which occur at the same time---in A's frame to be thought of as actually occurring simultaneously. Therefore, in the right-hand-side image (B's frame) I want you to think of "the universe" as the x-axis, which moves along the t-axis. (Do you see that B and C can then be thought of as moving through "the universe"?) Now, the causal structure---i.e., the light-cone structure, together with the distinction between past and future---becomes important for the following reason. In both graphs, null lines have to trace out as 45-degree lines; therefore, although "the universe" is tilted in B's frame, everything that moves through "the universe" has to move along a timelike worldline. Not only is it true that no particle can move through "the universe" fast enough that its world-line would have a negative slope (as if it moved down and to the right very quickly), but no particle can ever move through "the universe" so fast that the slope of its world-line is anything less than 45-degrees.
Make sure you understand this, because it's what I'm getting at in that paragraph that you disliked so much: although "the universe" is tilted and evolving upwards in B's frame, everything still can only move through "the universe" so that it traces out timelike or null world-lines.
Now, given this very different interpretation in which particles actually move through a particular hyperplane (absolute space, which may or may not be real independently of the particles that exist) that actually evolves (i.e., in absolute time), let me explain that paragraph better. Inertial particles trace out straight world-lines which are their proper time-axes (inertial structure). Inertial particles with non-zero absolute motion (B and C) can describe themselves as remaining at rest in "space", and light as propagating at the same rate in either direction of "space", by defining "space" as the hyperplane that's tilted towards their world-line as depicted in Figure 2. This is simple enough to see if you draw B's light cone in the left-hand side diagram: in an interval of t', light moves through x' just as far to the right of B as it does to the left. B can therefore use these primed coordinates to describe themself as "remaining at rest in space in which light propagates isotropically", as shown in the right-hand side image. However, this is not enough to fix the magnitude of c as being the same in B's coordinates as it is in A's. In order for that to be, B's coordinates need to be scaled hyperbolically with respect to A's, according to a Lorentz transformation. Therefore, distances in the space-time continuum of events that occur in the universe are determined according to the Minkowski metric.
Another way of thinking about this is as follows: assuming a Newtonian universe that's evolution is described by the Minkowski metric (i.e., the map of events that occur in the evolving universe is described by the Minkowski metric), given the requirement that light propagates along null lines while everthing else must trace out a timelike world-line, the space-time continuum of events that occur in the universe will be coordinated in local inertial frames just as it is in special relativity theory. Therefore, the mathematical theory is exactly the same, but an absolute simultaneity-relation has been assumed in order to reconcile SRT with a true passage of time, in contrast to Einstein's interpretation of the relativity of simultaneity which leads to the requirement of a block universe.
Now, to address a few of your points more explicitly: 1) I've answered; 2) it's perfectly acceptable to write about "uniform motion through the cosmic present" in a theory where I've already stated that there is a true cosmic time and a corresponding absolute rest-frame; 2) (again) at the point where two relatively moving observers meet, their light cones are exactly the same, but according to the common interpretation of the relativity of simultaneity, what's simultaneously happening on a planet in Andromeda will be different according to each observer. I'm arguing that this is wrong; 3) do you see what I mean about the x' axis being tilted with respect to x, the cosmic present, so that light will be described by B as moving at the same rate in either direction? In an interval of t', light doesn't move as far to the right through x as it does to the left; 4) (I just answered the first part, but also) it's not enough to simply rotate the axes to make light propagate with the same speed in either direction for B: the coordinates also need to be re-scaled so that speed of light remains the same finite value in all inertial frames; 5) they only need to be parallel if they're not moving at all relative to each other, and if that were so, the figure wouldn't illustrate much.
Anyway, I've done my best to handle your objections. If you do have another look at the paper and something still doesn't sit right, or if you see something else you don't like, I'll continue to do my best to explain myself for you. I'll be out of town for a few days, with only a phone to respond with, though, so if you write a lot again I may just wait to respond when I'm back.
Regards,
Daryl