I have an ihome radio at work and would like to play itunes I've downloaded on my iphone 3GS. Does it use my data plan while playing the songs? I see the 3G symbol turning while it's playing songs. These songs have already been downloaded on itunes. Thanks.
Do you mean songs in the iPod/Music function on your phone? If that's what you mean then the answer is no! If you want, go to Settings, General, Network, Turn Off Cellular Data, then play a song and you will see it works :)