Will this fit a 23" head?

I own four of these hats. I measured my head and I don't know how accurate because I was doing it by myself, but my head measured 22”. These hats look cute on and are pretty comfortable. But I have not worn them for more than 30 minutes or so. Not hours on end. If I pulled these down tight on my head, as far as they would go, I would say they were a little big. Definitely not too tight. They could fit a much larger head than mine. But if you just pull them down far enough to look cute, they still feel secure. A very small head might have trouble keeping them where they feel comfortable and might have to readjust them all the time to keep them from falling over their eyes. I would say I have an average head, and they fit me fine, but room for someone with a bigger head too. They have stretch. I think you would be ok with 23” head. That’s my guess though. Hope this helps.

Why would they have short white hair on them??

I understand your question as both of the hats I received have some sort of animal hair woven through them as well. Several other reviewers also were concerned about the hairs.

How long and wide is the brim?

The brim is 2 inches long at the center and tapers. The brim is about 9 inches wide. It does not provide much eye protection from the sun. The hat, in general, runs small. I pull on it to stretch it so that it covers my ears.