But there would be no glaciers in the middle of a fifteen-cubit-over-the-mountain flood. Maybe an ice floe, but no glaciers. And Genesis specifically has all life that had breath being destroyed, except what Noah and the boys had on the ark.
I'll bet you're correct - they likely have no lungs, and surely no nostrils. Whales and porpoises, though, have both, after a fashion. Were they on this boat?
I can't think of any animal that would have a problem with that,
Most mammals, at least when not in captive situations, have pretty strong "taboos" on in-the-family breeding. Where do you think we humans came up with rules about incest, after all? Chimps have the same rules...