I have made my new restaurant WiFi available to my customers at no charge. The system has been designed to seperate the back of the house (office) Wifi access , and credit card transactions, also through Wifi, from the free access for the customer base. Are there any securiity issues that I maybe overlooking. We are using Comcast for Business.

Secondly -- which is quicker-- Comcast or a dedicated or static T1 line.