Q: Do radio stations pay the artists for permission to play their song(s), or do artists have to pay radio stations to play their music (like for publicity's sake or whatever)?
A: artists get paid per play on an estimated basis, but only if their songs show up during the sampled times. this is also assuming the artist has jumped through all the various invisible mysterious hoops that need to be jumped through, such as getting the song registered properly in all the right places