1. Why i do not see a iRadio on my device: iMac(osx 10.8.5), iPad 2 and 4, iphone 4 and 5s. (ios7)
iTunes Radio is not supported in all countries yet.
Right now it is only available in the United States.
2. Air drop between my device does not work: iMac <> iPad, iPhone
AirDrop currently does not work between OS X and iOS. Only OS X to OS X or iOS to iOS.