Well, it depends on the exact laws of your country... but overall

No... if you're presenting someone else's art, you are supposed to pay them for that presentation...

Technically speaking for instance, when I cover a James Keelaghan song at one of my gigs, I'm supposed to pay him his quarter-cent royalty (Or whatever paltry sum it adds up to be)... The pub where I do most of my giggling pays into some level of SOCAN though, to cover the cost of such... (And according to the owner it's only a few bucks a month or so... He tells me he has to pay by the year, or it's such a small amount, he'll regularly FORGET to send it in! LOL )

Of course, there enters into it the question... do you think the original creator is ever going to find out you gave away the mp3s? I'ts really not likely....