There's a lot of music in the public domain, and some people create their own music, and while nobody is more scrupulous than I am about paying artists for their work, if something is long out of print and can't be had any other way, the best one can do is try to track down the artist and get some money to him.
Don't copy music otherwise, it's wrong.
Second answer is the only correct way to do it. Add the tracks to the recipient user's iTunes library. This won't work for purchased items since they're encrypted to a different key. You can only synch each content type ̣̣(apps, music, photos, etc.) to one computer at a time.