Well, it might be that he dumped you but still wants to see what you're up to. He could be having second thoughts deep down. Or perhaps he just enjoys seeing the snippets of your life without having to be directly involved. It's a bit of a mixed signal, really.
Yes, it's completely normal. Fanfic is a popular form of literature among many people, and your gf is no exception. It's just another way for her to engage with stories she loves.
It could mean he's still curious about your life. Maybe he has some lingering feelings, but not enough to get back together. It's also possible he just likes to keep tabs on you out of habit.
It depends on how you feel. If seeing his name among your viewers makes you uncomfortable or it's preventing you from moving on, then yes, block him. But if you don't really care, you can just leave it as it is.
It could mean she still has some curiosity about your life. Maybe she doesn't completely want to cut off all connections with you, even though she ended the relationship. It might also be a habit. She used to be interested in your stories, and it's not easy for her to just stop all at once.