This thread has multiple questions, but in my frequent AMS transits this year, here are some notes:
* For the flyer going OKC-ATL-AMS-OTP, all your flights are non-Schengen, so there is no passport, no security, no nothing - - just go to your next gate once you land at AMS.
* For flyers going non-Schengen to Schengen, the queues can be short, or mount up quickly and substantially; in that case, there is someone who will allow people with the tightest connections to come over and join a shorter line, depending on your departure time. The agent will call out "everybody with 12:45pm departures can come over here," then in a few minutes 12:50, then 12:55 as the minutes tick by - - be prepared to access that short queue as soon as your departure time is called.
* For flyers going Schengen to non-Schengen, the area sectioned off for U.S. and other passport holders with chips in their passports can go pretty quick - - if you head to the far left queue (highly recommended) there is a spot where one line dumps into three processing gates, instead of one gate per line; at these passport reader gates you enter a sectioned spot, put your passport into a reader, it reads it for up to 30 seconds, and then tells you to proceed and get a stamp - - no hassle, no questions - - just a machine then an automatic stamp from some person with no other agenda).