You don't have to be in Nashville. When I did the seminar last year at South By Southwest, a lot of people got mad because I said all this, but it is because it means they have to get off their butt. Individually afterwards they came up to me and thanked me for telling them like it is. But they will scan them. We send three songs and a note to who we think it would be good for.
Any format is good, but the fancy CD's with covers and all seem to confuse the issue.
Are you telling them you are an artist or trying to pitch a song. Just send the best ones you have. You can get eaten up in Nashville. I don't believe you have to be here. You also need to be prepared for rejection.