The Science of God is an excellent book that answers a lot of these questions that stem from a superficial understanding of the English translations of the Bible.
In the instance of Cain's wife, it hypothesizes the same thing that SentForth5 has stated, except that it supports it with medieval Hebrew scholarship to show that it is not a flimsy attempt to reconcile Darwinian evolution and creationism.
Gerald Schroeder is a superb scientist, scholar, and author, and reveals how juvenile and shallow a lot of the New Atheists are in their lines of questioning Biblical accuracy.