There could be several reasons. His stories might be boring, or perhaps they contain spoilers for something you're looking forward to experiencing on your own. Also, he might have a history of spreading harmful or unethical ideas in his stories.
Probably not. People usually have a lot of followers and viewers for their stories. Unless you are someone really important to him or he specifically checks who has viewed his story, it's highly unlikely he'll notice.
Most likely not. There could be hundreds or even thousands of people who view his stories, and one less viewer isn't something that would typically stand out. He'll probably be too busy creating new content or interacting with those who are more vocal about his stories.
No, it's not rude at all. Everyone has the right to choose what they want to see on social media. If her stories don't interest you or make you uncomfortable, it's okay to not watch them.