I'm trying to find a program that will let me create layered music from pre-existing sources. (ie. sampling, mash-ups, etc...)

A program that is basic, but does the following is all I need:

Can import tracks from a CD or MP3 Format
Can change the duration/speed of individual tracks (necessary to beat match)
Can cut and paste (edit) waveforms

That is all. Acid on the PC does all this perfectly, but the best I can find with a mac is using both Peak and Deck back and forth, which is getting old. Something easy to learn/user friendly is also nice.