Answer:
Take one out and scratch my head, I am now black but once was red.
Be sure to shout for its answers are weak, but there is no language it cannot speak.
I am the tool, for inspiring many. Buy me in the store, for not much more than a penny. Don't overuse me, or my usefulness will go.
Take off my skin, I won't cry, but you will.
It is a path of cow juice spread across the sky but cannot be seen by the naked eye
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?