Can I in fact download mp3's if I have not offered my file to share?
Well, with Kazaa, if you chose to option of not sharing any files, you get stuck in ques for nearly every file. I clicked on this, and suddenly both running downloads entered queue. I wonder why.... So be careful with that option.
And while I'm asking dumb questions, will I get a faster download from somebody who is listed as cable or dsl than from somebody on 56K?
Yes, provided they've got the bandwith ( ie not many other people downloading from them ). So shop around a bit. You should get up to 50 kbs. Enjoy it.
If WinMX or whatever program you use is being slow, or not working, try another one. Kazaa, Morpheus, as RadarContact mentioned Gnotella. One will work.
Anyway, I though broad band ISPs blocked the ports used by file sharing programs? Or have they given that idea up?