Can you wash this in a washing machine?

I haven't tried yet to wash it but my son won't let it out of sight. He loves it. I was going to use the dry cleaner stuff you get at the grocery store to make sure it's clean but also more gentle cleaning. I've used it many times before on other items and everything has turned out well and clean. Hope this helps you.

How will it fit on a 5’7 man?

I am 5'10'' and it fits fine. May be a little long on someone shorter.

Is this the authentic color of the one from the movies?

I got this for my son and he is a big fan of Clint Eastwood's. He's very happy with the color and he said it's just like the one Clint wore. Take that for what you will. I never saw the movie.

Do they make this in kid sizes?

I believe it's an adult only one size fits all or fits most. You might find something similar in a youth size but I never looked. You might be able to buy similar material and easily make it to a size you need.