Answer:
I am bought by the yard but worn by the foot. What am I?
My full powers come when my makers are dead. I await a heavy hat to put on my head. What am I?
I'll bring out your bulls and slow your roll. I may even come out of your skull.
Though desert men once called me God today men call me mad. For I wag my tail when I am angry. And growl when I am glad.
I'm white and used for cutting and grinding. When I'm damaged, humans usually remove or fill me. For most animals I am a useful tool. What am I?
The answer I give is yes, but what I mean is no. What was the question?