Yes, I'd really like MrG to have an honest go at this but I'm afraid it will take too long for the answer to come through from America.
If God could harden the, Pharaoh's heart, it stands to reason that He could also soften the, Pharaoh's heart, so the only lesson to be learnt hear is that a literal belief in this kind of god is a belief in a homicidal despot who uses humanity as pawns is a game not dissimilar to the gods of the ancient Greeks.
These stories were written after the events by people who believed themselves to be exclusively chosen by God. Every event based in natural order was then seen as a God driven event to be woven into their religious history.
Prima facie these OT events describe a god unworthy of any form of worship. Clearly these stories are not to be taken as absolutely literal, they reflect the potential power of God, the political intrigue of the age, the absolute self belief of the Jews as being chosen of God and a good deal of poetic license.
It's not unlike Abraham sacrificing His son and then at the last minute replacing the son with a ram found tangled in bushes. This is a moral tale, human sacrifice was prevalent in this age and still ongoing in the age of Moses. By sacrificing the ram instead of His son, Abraham was showing the people that God would accept an animal sacrifice instead of the despicable practice of the ritual killing of humans. There are baby steps of moving people towards higher degrees of being civilised. The killing of the first born is in this mould of story and relates how even the most powerful have no power compared to God.
