Since it is Saturday, I also tried to orient myself about when these passages were written. I found a great article by Walter Brueggemann and some other interesting information in my dad's New Interpreter's Bible. (BTW, the intensity with which Christian Fundamentalists attack scholarship and dominate on-line searching for things as standard as JEPD, is stunning. So, for example, I'd like to know if the documentary hypothesis is still valid and consistent with recent scholarship, but the internet is so crowded with angry anti-intellectualism, that I cannot easily research the topic.)
Joseph Blenkinsopp's introduction to the Pentateuch in the NIB, there were two main authors of the Pentateuch that were writing post-exile. The first was the Priestly writers, and the majority opinion is that they were writing around 5th or 6th century BCE. The Priestly traditions, e.g., demonstrates only a one-way promise from God to Israel. The other tradition, Deuteronomists, wrote at a similar time, but, e.g., provide the two-way covenant that only comes to fruition if the Israelites follow the law. The earlier traditions date back to the Southern (J for Yahewist) and Northern (E for elohimist) kingdoms, pre-exile. (~1000 BCE)
Brueggemann points out that "Our own interpretive work ... is not to reflect on an ancient history lesson about Egypt or about cult, but to see how this text, in new, demanding, and dangerous circumstances, continues to offer subversive possibilities for our future." He notes that "pharaoh" most certainly plays the role of Babylonian and Persian rulers who, at the time of final authorship, had recently taken the People into exile. The exodus out of Egypt certainly existed before the Torah was formed, but it was formed in a manner as to point to modern concerns. "Texts are never innocent or disinterest, but are always acts of advocacy."
Considering that years later, Jewish authors would attack Rome by reference to Babylon in John's Revelation, I find Brueggemann's words quite compelling.