Well, I think pre-ordering games is a bit risky. I have seen many games that are launch with bugs and incomplete content. So, if you pre-order and the gameplay is quack, that's a total waste of money.
I usually start with normal difficulty. I think that's more balanced for most games. I don't like easy mode as it's too soft and boring. Hard mode can be very frustrating too. So, I prefer the normal difficulty level.