You have mentioned two topics that are key in trying to reconcile science and faith. Regarding the flood, that has been discussed with some detail in the Forum topics “The Problem with the Flood” and “Continuing Discussion on The Problem with the Flood.” I have doing some further research on this, most recently with the new (secular) book, “The History of the Ancient World.” The author, Susan Wise Bauer says that the amount of ‘mythic’ flood stories seems to indicate that there was likely a real, catastrophic regional flood in pre-history, either in Mesopotamia or Black Sea region. It seems likely that it was before 9000 years ago, quite possibly before 12,000 years ago. To be sure, at that time boat-building capabilities were pretty primitive. There is evidence of less notable flood around 4800 years ago when there would be somewhat more advanced boat building.
Regarding Adam and Eve and Haarsmas’ Origins book, I lean more towards a variation of “Adam and Eve as a Pair of Ancient Ancestors” and “Variation:Group of Ancient Ancestors,” where Adam and Eve were not the very first humans, but were the first ‘spiritual humans.’ Their spirituality came from an encounter with God that is a partly literal, partly figurative telling of the Genesis account. And this “spiritual” nature spread (probably at the time there was a bottleneck in homo s. sapiens) to all surviving behaviorally modern humans, making them the spiritual parents of all humans. See Finding plausible answers to The Problem of Adam and Eve for more information. @aleo tells a slightly different version of the scenario.