Indeed God being omnicient, knew that He would have to flood the earth to try and erase the many times man fell from Grace.
God knew the story from ending to beginning. So yes, he knew he was going to flood the world. What I think is important, though, is why he flooded the world, not just the fact that he flooded it.
I believe it is literal. The story says there was widespread wickedness in the world, God gave them a chance (years) to change themselves and they refuse to. God knows what's going to happen because he know our nature since he created us.
But since we wanted to see if we can do things away from him, he sits back and allow us to do us. He already knows what the outcome is going to be, but we don't and most times wouldn't listen to him if he told us what to do.
1) God is omniscient and does have a plan, though not necessarily revealed to us.
2) I don't believe man fell. The 'Fall of Man' is a Catholic interpretation that has stuck with the Church. Man was not a perfect utopian being in the first place, though there was a single event where he first sinned.
Original sin is a Catholic invention. But that's another whole hub in itself. Compare to a Jewish interpretation of man which is quite different from the Church's.
3) I think the Noah flood is not to be taken literally any more than the Creation Story. They are allegorical. Though bizarrely, virtually every worldwide ethnic group does have a flood myth in their ancestral history so I'm told.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.