Ok LG I read part 1. I commend you for putting these thoughts to words! God will always bless our focus and recognition of Him, aka worship of Him. 

Full disclosure, I lean old earth over young earth but I am not certain either way. I affirm God created the cosmos, and to think otherwise is a mistake with profound negative consequences to humanity and society. However, I reject the argument made by many Answers-In-Genesis types that a non-literal interpretation of Genesis is somehow an attack on inerrancy or inspiration. That assertion is a classic example of the fallacy you described: begging the question.  The original audience of Genesis was prescientific, and so there is no reason to think God was making scientific claims. Rather, it makes more sense that he was making theologic claims. I agree Genesis doesnt borrow from other cultures and I think its more likely a polemic against those other cultures with seemingly similar stories. The God of Israel, not the gods of Sumeria, created the world.

You rightly describe the limitations of science, but then try to argue young earth from science. The problem with that approach is that for every example you offer, a militant atheist can respond with 10 seemingly more credible counter examples. Better to argue from the worldview level as you did (ie. natural science is not the final arbiter of truth)...imho. 

I hope my feedback is not too harsh! I hope you keep pondering and these topics and I'm sure they will bear fruit!