In my limited experience, GM shawls are gone before the doors open to the public. I know there have been shawls at sales (such as the one in Paris) in the past, but those are really hot items. I was actually one person short of being in the first group to enter the last NY sale on the first day it opened to the public and I didn't see any shawls.
As others have mentioned, you can bring your phone. I use Verizon and evidently I had adequate service because I was able to receive messages and place two calls.
Selection is anyone's guess. At the September sale there were many, many different styles of shoes.