While in Memphis, you must visit the Peabody hotel in the afternoon to celebrate the 'ducks.' I'l write a few bits for this evening. Also, in Laguardia, don't take a coach for transfers into Manhattan, car service will be much better for you.
Please, approximately where are you staying in Memphis and in New York?
Agree with everyone regarding visas...you will, however, still have to have proof of identity for each of you for the domestic flights, so don't pack your passports too far away...in fact...DON'T ever pack your passports away...keep them with you!
Are you by chance flying on Northwest? I ask only because of the itinerary.
Best regards
Fr Bill