i think its gotta be audacity. its definantly been the best program i've used. it is really easy to use, and it still has all the features you want
Just use some commercial software - like Adobe Audition 2, as long as you r not selling your music!
Cool Edit is OLD! Now it's know with the name of Audition, since Adobe bought it
i use ableton live, and i like it alot, but it isnt for free aswell