Blue crayfish sexes?

Hey guys, I've several questions here:

I was looking at some of the blue crayfish my LFS was selling. The thing was, they couldn't really tell which ones were female and which ones were male since the crayfish were pretty small (probably about 1" long). I believe the males have one extra swimmeret where the abdomen and the thorax meets, but the LFS guys said it was difficult to tell when they're that small. I wanted a male and a female, but if what they say is true, then how would I go about doing that? They do sell large ones, but they're insanely expensive.

Also, I saw that the crayfish had different colors. One was very pale blue with a hint of light brown/red on the sides of the head, and the other was darkish blue. What's the difference between the two? They listed them both with the same name. Could I breed the pale blue one with the darker blue one?

Any help would be great! Thanks