Answer:
Tickle with your fingers and a song it will sing. Be careful, though, you may break a string. What is it?
Casper was a friendly one and Demi Moore made a clay pot with one.
A king wears one on his head.
I am the first you ever saw, what greets you every morning and what goes out in the end.
What can you lose that will cause other people to lose theirs too?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.