Re: Question regarding use of famous quotes
I think you'll avoid problems getting permission further down the line if you keep it short. But the time to worry about getting that permission is when the story is about to be published.
Apart from ethical considerations, violation of copyright can lead to big problems for both the writer and the publisher.
As for doing the songwriter a favor: I used to have a friend (the operative words being used to) who was always doing me favors I neither asked for nor wanted -- sometimes, in fact, I had already made this quite clear -- and then she expected me to be grateful. Somehow, I never was.