Can I purchase BHC hardware and configure it to use another VPN server?
The VPN configuration is not user accessible. It is burned into the firmware as we prepare it for you. The hardware only works with the servers you order from us.
What is the difference between the external antenna and internal antenna models?
As delivered, not much. The internal antenna is only about 1dbm less sensitive than the external antenna. The flexibility of being able change to a larger antenna is good if you need it. Also, if you are in a RV or on a boat then being able to install a large antenna outside of your vehicle and run a cable inside is a wonderful option to have.