I made it ! It was 9 hours from Munich to Newark Liberty International Airport (in the New York area), 2 hours of stressful connection at Newark, and then another 6 hours to Seattle.
At Newark (this is standard for USA international arrivals) you have to go through passport control, get your bags, clear customs, re-check your bags, and then go and stand in a very long line to go through TSA security again for your connecting flight. So the lesson is : try to fly directly home from overseas. If that is not possible, pack your patience and make sure you have two hours to connect, since one hour will not do it.