It's hard to explain without ruining the story. Your character has nothing to do with the character from the first one. You are a special Big Daddy from the beginning. Personally I never used the drill at all really. Once in a while just for the novelty, but I think it sucks compared to the other weapons. You aren't slow and lumbering at all, and aside from the few parts where you go underwater you don't even realize that you are in a suit.