They are impressive. This is an exaggeration. YECs sometimes claim too much because they are trying to prove that everything arose instantaneously. PC does not claim this. This is a reference to the birefringence.
Answer comes there none.
An Intelligent Designer would be expected to use the physical laws he had created. I have no problem with natural selection fine-tuning an already present design. These issues are crucial. I will then revise my model. Although interesting and portentous events have occurred since, from the flowering of dinosaurs to the origin of human consciousness, we do not exaggerate greatly in stating that the subsequent history of animal life amounts to little more than variations on anatomical themes established during the Cambrian explosion within five million years.