That sounds so cool, Jim! I love theatre music for kids!

Original music (Or any other artwork) is inherently copyrighted in my country (Canada), and it costs nothing. But to prove the work is yours, you send yourself a copy through registered mail and leave it unopened. That way, you have proof of the date it was first written, should it ever be contested.

In the case of your friend, he would hold the inherent copyright for the music and lyrics, and I would hold it for any piano arrangement I'd create for him (like a dual inherent copyright). Pretty sure that's how it goes, anyway - if you're not Canadian you might want to check and make sure it's the same in your country though.

daylia