If you have one of the gray hard drive icons on your desktop, sometimes named MacintoshHD, then you probably have no partitions. Mine show up as two distinct gray drives on my desktop, even though they are not literally physical drives. That's the way Apple does it.

Your alias should point you to the original file by doing the get info thing.

In case you return later, here's a synopsis for you. You want to install the newest version of LimeWire for OS 10 into your Applications folder and do the install while booted into 10. Then, when you run LimeWire in the future, your completed downloads will go into the Shared folder inside of the LimeWire folder inside of the applications folder inside of the hard drive icon.

Don't try to work with files within the LimeWire window. That will only add to your confusion. The files reside in the Shared folder. That's where you should be able to work with them.
Normally, in OS 10 and with iTunes 4, merely double clicking on a new mp3 file automatically adds it into your Library, and via the iTunes preferences, you can decide if it makes a copy for the iTunes Music folder, a handy thing to do. Then, if you throw things away in your shared folder, you haven't affected the Library, only the original download.

I'll check back, but maybe someone else will come by with additional perspective, ie, something I've missed, or erred on.