Ah--JFK!!! I'm nonreving today to meet hubby for dinner and do his laundry (Yes, I know, what a good wife!!)

We use a seat request card as a substitute for boarding pass. TSA accepts employee passes all the time. Pass thru TSA and wait at the gate for a seat assignment. The difference is one security check for all gates in one terminal (not like FRA)
Immigration might a huge pain--just read all the signs and ask if you have questions. No cel phones/cameras at immigration! The queues are not well managed, so be patient. You can take a look at the airport layout, and I recommend that because JFK is a bit bizarre. Maybe even print a copy for reference.
Have a good trip!