Speakers in the ceiling are an option - I don't have any so can't speak for any drawbacks, e.g. sound through to the floor above, etc. You would wire those through to a Connect Amp. They tend to be streamline and there are quite a few on the market - even wall ones that don't even look like speakers. One place where they would be ideal would be the bathroom/en-suite/etc. If you get ones that are suitable for those rooms, you will be able to play whatever you want through them. You could group it with the bedroom one, or have it on its own, etc.
Regarding the smart tv: the Bar will accept the TV's audio as an input so you can push the TV/blu-ray/dvd/sky/etc. audio out through that speaker, plus the Bar will play the stuff that you can play through any other Sonos speaker. So you get high quality sound from the Bar rather than through the TV's speakers. I don't think that it will push the TV audio out to other rooms though - I could be wrong, though.
Bose are good - probably around the same price, but you get so much more with Sonos.
I think there is a limit of 32 sonos devices that you can have on the network. They create their own WiFi mesh network which is separate from the house's main WiFi network, so your music playing won't affect your computer's download speeds and vice-versa.
You can stream music content from servers on your network, online music services such as Napster, Spotify, Deezer, etc., from your iPod/Phone directly (though you probably want to give your iXXX power as it's streaming from the device and will eat your phone's battery). We use Napster as the music service. It's £9.99 per month for unlimited music with no ads - we got 6 months free + free bridge when we bought the first sonos play:3 at the start of the year.
The controllers for sonos (e.g. on Android, iPhone, iPad, PC, Mac, etc) just issue commands to the sonos devices on your network. They don't stream music to the speaker via the phone. That means that you can tell a lounge speaker to play radio 1, the kitchen to play radio 4 and the bedroom to play some 80's hits, then turn your phone off and they would all continue playing. It also means that your phone's battery isn't being drained.
Have a look at the sonos website and read the reviews. Have a look on YouTube - search for "sonos", then you will see some good reviews. Watch Tom Strong's unboxing video - it's really informative. I would recommend watching at least the first 8 results from that search.