It is very difficult to know for certain that basic constants (like the speed of light) have always been the same or are the same everywhere in the universe...
Dean,
You touch on oneajor issue modern science is stuck on, Uniformitarianism. The idea and belief, absent observation and test, that processes, values and measurements have always been constant. This idea has very little fact involved. Today, tectonic plate movement may be x, but 10k years ago, or more, it may have been x*2,
Which is just as valid an assumption as a uniform process....
We all have the same facts and evidence, it is the lens that we choose to observe or assess with that determines the answers we arrive at.
I happen to hold a biblical world view, so my lens is not as liberal or free as a non believer. IOWs, I look at things through the lens of both observation where possible, and description where applicable. I have not found incongruences that are beyond acceptance.