Yes - now when you purchase Xfinity Home, you own all of the equipment -- including the Touchscreen. Typically the cost of the equipment is spread out over monthly installments, but it can also be purchased outright.
Most areas of the country transitioned to the Touchscreens being purchased as part of the sytem over the last year or so. Prior to the transition, all equipment was sold with the exception of the Touchscreen, which was leased as part of the monthly fee (and would need to be returned if service was stopped).
If you are an existing Xfinity Home customer, you can check your billing statment, which will indicate "Leased Touchscreen" (or similar) in the Xfinity Home section if you currently lease the Touchscreen.
If you have any quesitons, just give us a ring and we can confirm everything with you.
To silence a sensor, choose the Settings icon in the upper-right corner on the Touchscreen and Choose Sound, Sensor Sounds. Enter your master code.
Here, you will see a list of your sensors. You can either change the associated sound, or check the box to "silence."