Answer:
My voice is tender, my waist is slender and I'm often invited to play. Yet wherever I go, I must take my bow or else I have nothing to say. What am I?
I lose my head in the morning and regain back it at night.
I increase head turning rate tremendously for girls at the beach
I have all the knowledge you have. But I am so small that I can fit into your hands. What am I?
People buy me to eat but never eat me. What am I?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.