No, Sonos does NOT use your wifi network at all. It plugs into your wired Internet connection at your router, and creates its own wireless network, which is proprietary and not standard Wifi. In fact, that is the entire job of the Bridge. Sonos wireless network is a mesh, meaning all sonos devices in the network can relay signals. So the more sonos, the better the network, the better the range of coverage.
I have my bridge setup right next to my computer modem. The sonos speaker I have linked to it is approximately 20 feet away through 2 walls. It receives perfectly. I have run it outside as far as 30 feet through 3 walls with no problem. Great system.
Not sure I understand. Are you asking if you can use Sonos speakers for TV audio? The answer is yes, but not with the bridge. The bridge issued to connect the sonos speakers to the household wifi. Sonos does have an (expensive) sound bar product meant to be used as alternate speakers for the TV. Check out www.sonos.com