1. Don't overestimate my physics knowledge. I have taken a few college classes of it, sure, but I'm no expert. It's not even my major. I had to give a lot of thought into my response, that's true enough.
2. So the properties of the lower dimensions continue to exist, but warp a bit when looking at higher dimensions? Interesting if accurate, but I doubt this would forgo the properties that light has in the 3rd dimension.
3. Many people on here try to do that. However, it'd be a lot easier on yourself to consider more of scripture to be allegorical than to try to take it literally. Heck, the bible never explicitly states the age of the Earth or universe, people derive that number by counting back through the generations of individuals in the bible. Given that the modern text is hardly complete, it would be fair to suggest that some of those generations are missing. Furthermore, no change in dimension is going to help you reconcile the various biological errors of the bible, or its internal inconsistencies. You aren't dealing with observations of the last 50 years, there are parts in that book known to be incorrect since ancient times, like how it gets the amount of pi incorrect.
4. Asking a person that doesn't believe in deities this question is rather odd, since I don't ascribe qualities or powers to things which I don't believe exist. From a fantasy standpoint, magic, why not?
5. Scripture never claims that any of these events caused a change in physics. In fact, scripture often implies that the world is highly stable and unchanging. Something that your change in light speed notably lacks is a point. Slowing down the speed of light after established life already exists complicates matters and could lead to the universe falling completely apart, why would a deity bother?
6. The background radiation of the universe and the fact that we can observe the expansion of the universe and trace it back to a single point.