Spam Up,
you can take youngskywalker's comments with a pinch of salt, European licence holders (and I am one) sometimes enjoy to make derisory comments with regard to FAA qualifications, I think to somehow elevate the superiority of their acheivments. It is a documented fact that both the licence's work as well as each other with regards to safety requirements. Your oral exam will be as long or short as the examiner deems necessary to evaluate your knowledge, if it takes longer, you can be assured you are being given every opportunity to convince him you know your stuff, if it is short, well done, he know's you know. Contact your next sim provider and they will tell you what they require for you to qualify for the FAA ATPL on your next sim check. Good luck. And don't forget to get an FAA medical.