No.  But a guest network will, with the added benefit of keeping people off your local network.  Almost every router made has the capability of setting up a guest network.

No.

BOOST follows the same radio protocols as the players. In most respects it is simply a player with the audio details removed in order to reduce costs.

EDIT: Following jgatie’s scheme you would need to change your current WiFi credentials in order to block unauthorized users, then set up a “Guest” account that you could give out to visitors. A Guest can access the external Internet, but not your local network. in general, this will not have much impact on guest users unless there are certain local items that you would want them to access, such as a printer.

If your current router doesn’t offer a Guest mode connection you can easily add a Travel Router with a different SSID and let your guests connect to that.