Answer:
I am quick when I'm thin. I am slow when I'm fat. Wind is my worst nightmare. What am I?
I need to be taken from you before you can have me.
I am often sold by children entrepreneurs in summer time
Sometimes I am white, sometimes I am dark. Most people love me. What am I?
I saw the dead bring forth the living. I saw the living bring forth the dead. What did I see?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.