He wrote slowly because he was writing seriously or because he was facing some difficulties that made it difficult for him to finish a piece of work quickly. It could also be that he was not satisfied with his writing and needed to spend more time thinking and improving. No matter what the reason was, it was important to ensure that the quality of his work was recognized.
It could be that he really likes those stories and thinks you might not have fully grasped them the first time. So he tells them again. He might also be forgetful and not realize he has already told you those stories.
I'm sorry, but I don't actually know what 'the stare story' is specifically. It could be about a particular stare that had some significance, like a stare between two rivals in a tense moment, or a stare that held a secret message. Without more context, it's hard to tell the full story.
I'm not sure specifically which 'the stare' scary story you mean. There could be many different ones with this title. It might involve a creepy stare from a mysterious being, like a ghost or a monster, that haunts the protagonist.