These are a very tight fit, I purchased L/XL for my size 45 shoes and they are a struggle to get on. Having said that, once on, they are a great fit, but perhaps they are best left partially on the shoe and over the cleat to make things a lot easier.
I haven't had to wash them yet so cannot comment on this. They were purchased to replace a pair of Castelli Belgian Booties which proved to be of very poor quality, and whilst these have already developed a small hole near the toe (after about five/six rides), that could be down to a recent fall I had so cannot be sure.
All in all, they seem like a decent product.
Perfect for keeping off the chill without that boil in the bag effect.