I have only three rules for air travel -

1. Avoid JFK
2. Avoid ORD
3. Avoid JFK

While I smpathize with everything you went through (except the part about the pregnant lady at Immigration - thats not Delta's fault, they have zero clout in immigration, rant about immigration and the fact that they don't have line for expecting moms), a big part of me also says when you fly to JFK you have to expect this type of disaster, we all know it and really shouldn't expect anything else, if it isn't a disaster its a bonus! which gets me back to my rule about JFK - avoid it!