Every living things has C14. A worldwide, one year plus flood would wash and mix things pretty well. Since it is a fossil, there is NO original organic material for the C14 to be in. Frozen bones have been found and will have C14, but evolution labs will not test them, because that means they aren't old. A creation group is building a tester.
Nobody understands what the first part of the sentence means.
A reversal means it went down to zero and back, there was no protection. This happened several times. My quess is this means the radiation could then physically knock particles out of things and ruin an assumption of constancy. The calculations were make based on the moon's size, not the earth's size. There are no physics known to suggest the amount of moon dust found, unless the moon is young.