Great post Sharke.

 I would have been surprised if someone would have stated that they hear the entire song along with all the parts. I think Herb was the closest in saying that he sometimes hears a melody.

 I usually don't hear a melody unless I am playing an instrument .I say usually because sometimes it happens. For me, part of the fun is in building up an arrangement like a painter paints a canvas.

 I usually start with a rhythm track because it is the only way I can play in correct time. Even if it is a click or one drum. By the time I start with the rhythm though I have already played around with some kind of melody and it is ready to go to track even if it is rudimentary. I have started to use a looper to play an idea and try combinations with it in real time. This really helps to get ideas happening fast.

  I have one I'm working on now called Mekolypse that is still in the works, sometimes after all the groundwork is layed not even half the job is done and the fun has only started.