Sounds like there are long layovers, but make sure to build extra time in. It can be a wait for a wheelchair.
You can request a wheelchair when you arrive at the airport, but giving Delta an early headsup can't hurt.
Definitely pink tag and bring the walkers, for the exact reason -- so they can be mobile after the attendants bring them to the gate to wait.
Atlanta and JFK happen to be airports with electric cart transportation.