Oh, very nice review. I've read thee Kings so far and they were ok for me, but I didn't really enjoy them. But this one is interesting. Due to my job I'm deep into this gender subject.
There was also a huge discussion, when J.K Rowling told her fans, that some of her characters in Harry Potter are gay or have a dark skin color. This wasn't mentioned in the book and some people where very angry. But who the hell cares?
Like all of King's books, this one is very violent and graphic at times, which can be hard to read, but I find that action is what makes the stories exciting.
I agree that it shouldn't matter if characters are gay or have a dark skin colour, but in this case the story is set in rural America (the Appalachians), where racism is still a pretty big issue. If they did purposely leave out the skin colour until later in the story, it would have been an interesting decision to make because of the context.
Also, there's the issue of imagining a character one way for most of the book, and then having to revise the image in your mind, which is a bit jarring.