Does AppleTV also do the AirPort Express Job?

After installing AirPort Utlity 6.0 my "old" AirPort Express (2008) is NOT reachable anymore.

I have tried to reset it many times.

From my old eMac running 10.5.x I am at least able to see my AirPort but at the end of the process it always says that there was an error while restarting the device. (I've always used the device to "Join current network" for AirTunes).

Since I'm fed-up with this and I'm planning to buy an Apple TV device I wanted to know if it does the same job as the AirPort Express, in terms of playing songs and purchases wirelessly to my Home Theatre System.

Also I've noticed that from my iPhone I am able to send the audio (with no delay at all) to AirPort Express from videos/YouTube/etc... Why doesn't it work from the Mac except with horrible third-party software like AirFoil???

Thanks

L