Great looking snake! Welcome to an awesome hobby.
On the mite issue, honestly...they are a nasty thing to get rid of completely since they can crawl out of the cage, lay eggs, then crawl back in. A wash of the cage and snake might not eradicate it.
What you need is called Provent a Mite. It lasts on the cage for a solid month, so the critters can't come back in. Look it up and order some. It took care of our problem easily!