Answer:
I cost no money to use, or conscious effort to take part of. And as far as you can see, there is nothing to me. But without me, you are dead.
There are two meanings to me. With one I may need to be broken, with the other I hold on. My favorite characteristic is my charming dimple.
Who is it that rows quickly with four oars, but never comes out from under his own roof?
My teeth are sharp, my back is straight, to cut things up it is my fate.
What loses its head in the morning and gets it back at night?
What language does a billboard speak?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?