Well the most obvious is ... bible-sense is not fathomable in the modern world
even if it were to be true. The "best explanation" (within fathomable) is what you mean of course.
Not really. The global flood is completely indefendable.
Times change and I've seen datings of findings move about, to fit various other elements which would be contradicting otherwise. Whale bones found way up in the mountains, means moving the
age of the whale bones back to match the estimated age of the mountain to
when it arose for example. Or IIRC the theory they shifted up those mountains after a considerable time by earth rumbles and tremors or earth / plates shifting. Perhaps its acceptable that both happened and there are two defenders of these ideas.