Proof of radio airplay. Mentioning that you were Mrs. McGillicutty's star pupil in your fourth grade music class won't help you snag anything but a few laughs. Leave it out. Just one if your pitching your material to another artist. If you have more than one song to pitch, put them on separate tapes.
Nobody likes to search a tape for the song they want to hear.
If they don't like song number one, they'll hate you every time they have to search the tape for song number two. If you are pitching yourself as an artist or band, three songs is plenty. Many people are compelled to slip in a fourth or fifth song. Not a good idea. It makes you look like you don't know the rules the industry likes to see you play by.