I have the Edirol, and a bunch of other palm devices that I use with my Mac.

Angelo is right, when you connect the Zoom(or other recording device) with the USB cable, it will come up as a remote drive. Be careful, though, because the iTunes can upload sound files automatically from any media that is connected, (which you don't want to happen, because it tends to convert them to the Apple compressed format, and then hides them away) so make sure you set preferences for both iTunes and iPod so that it doesn't do anything automatically--

Rather than connect the device by USB, though, I find it easier to just pop the memory card out and then pop it into my card reader. Transfering files is usually faster, I don't have device interface complications, and I don't have to keep track of which cable fits which device.

At any rate, you can listen to your files in either iTunes or Quicktime player. You have to load the files into iTunes, and fool around with all those aliases and playlists, though. You can get VLC, which is freeware, and allows you to simply drag and drop a file to play it, or to create a playlist(which quicktime doesn't do). Don't get me started on an iTunes rant--

There is also MPlay, which is shareware, and is similar to VLC with some editing features.

As to editing--well, you can do that in "Garage Band"--though it is another program that has does things the way that Apple wants to do them, rather than the way that simple or straightforward. "Audacity" is a nice, basic freeware, and Amoeba Fission is good and inexpensive. Sound Studio was once a very simple recording and editing tool, but it has gotten big, with a bigger price tag--