Big post, so I will just deal with this chunk.I'll simply discuss irreducible complexity since you brought it up. I know it's widely claimed that irreducible complexity has been totally discredited, but that really isn't true.
Irreducible Complexity (IC) makes the claim that there are features that could not have evolved because there are no possible intermediate steps. And we know something is IC when removing one of the pieces would make the rest of the assemblage useless.
That is what Behe, Mayers, etc claim?
There are two glaring errors in this reasoning.
1. At a previous time, there is no reason so suppose that the other parts of the assemblage did not have some entirely different useful function. This has been shown in numerous cases where claims of IC have been overturned. A reduced clotting cascade and a simplified immune system still works. A major component of the bacterial flagellum was foundin simpler form to do something entirely different (an injector system).
All we have seen is ID proponents move to the next hopeful item every time research debunks their last claim.
But this misses an even more fundamental error in their thinking.
2. Evolution does not walk in straight lines. Today's seal might one day become as independent of the land as a whale, or might re-colonise some isolated land somewhere and gradually lose its marine capabilities. No way of knowing.
Likewise when we look backwards.
There is NO WAY to rule out every possible evolutionary pathway to a current biological structure. You would have to have omniscient powers to KNOW, and RULE OUT, any possible pathway to the structure you see. It could have gone through intermediates with entirely different functions. It could even now be a reduction in structure from an even more elaborate structure in the past.
So ID fails even in principle. Its a flawed approach that only sounds plausible by an argument from ignorance...."I cannot see how X could evolve, therefore it cannot have evolved!" IS NOT A SCIENTIFIC ARGUMENT. No matter how they try to dress it up.