I say do everything you just said. Send 2 or 3 mp3's. Put links in the signature of your email. As for the 3V or 1V versions? I can't help you. I send full songs, but things change from verse to verse usually, plus intro's and outro's. So I wanna get all that out there.
Also, I think it's good to be short & sweet with anything you plan on saying in the email. If they want to know more, they can check the links you hopefully added at the bottom.
Appreciate that fataltone. I'm gonna check that out right now.