The way i was told to tell a chickens sex is to hold them up by there body and if there legs hang down there male if they pull them up then there pullets so you can tell the sex now
I ordered from Oregon and also wondered if my chicks would make it such a long distance, plus, the weather here was only in the 50s. I am very happy to report that all my chicks showed up healthy, happy, and hungry and have been doing GREAT ever since.