Questions about Warrant Officers

Factual Questions
1

  1. What exactly are the duties of Warrant Officers? 2. How does someone in the military become a Warrant Officer?

  2. What does an infantry Warrant Officer do? Artillery, etc. etc.

  3. I know the U.S. Army Military Police have Warrant Officers as criminal investigators, but how do their duties differ from commissioned officers?
    Thanks for your help! I have been wondering about Warrant Officers since I was an Army MP in the 60’s. Never could get a straght answer then, hope I can now.