WOW--that is a treasure trove of travel tidbits! The key is actually going anywhere in EU before all of Germany goes on vacation July 1. Our BP friends made it fine out of AMS but had issues with domestic flights to CVG. Their employee wouldn't listen to me and had them do double leg next day after $$ hotel JFK. I suggested DTW on entry, then CVG next AM. Cheap hotels, too. Oh, well--this is great info and good lesson using LCC's. (my family did similar to get from AMS to Rome) and they traveled early-mid June.
Sounds like you had a good time--thanks again!