@Maclibrarian: Theoretically, those tasks should be possible with the upgraded version of the DS-2 software. As noted in the review, though, the software doesn't work very well.
A better approach would be to buy a proper audio editor such as Peak LE, Amadeus, or Sound Studio and use that. If you have an Intel Mac, check out Adobe's upcoming Sound Booth; the demo I saw at Macworld was impressive.
For a primer on audio editing, see my article http://digitalmedia.oreilly.com/2006/10/26/quickstart-digital-audio-editing.html