A common theme is family. Kanna is often depicted as becoming part of Kobayashi's family, and fanfics explore how they interact as a family unit. Another theme is friendship. Kanna makes friends in the human world, and these relationships are often a big part of the stories.
Definitely not. Fanfiction should stay within the boundaries of respect and legality. When it comes to a work like 'Miss Kobayashi's Dragon Maid', the focus should be on the positive aspects such as the unique friendship between the characters, the cultural elements, and the fun adventures. Sexualizing a character like Kanna is unacceptable behavior.
One popular type of Kanna Kamui fanfic is those that focus on her daily adventures in the human world. For example, some fanfics might depict her experiences at school, making friends, and learning about human customs in a humorous way.
One popular kanna dragon fanfic might be those that explore her adventures in a magical realm. For example, a story where she discovers a hidden power within herself and uses it to save her dragon friends from an evil sorcerer.
Think about the setting. It could be the same as the original or a completely new world. If you choose a new world, describe it vividly. For instance, if it's a world of floating islands, explain how the dragons and Kanna interact with this unique environment.
The Dragon Maid manga is indeed still ongoing. It has a dedicated fan base and the creators are committed to bringing more exciting content. However, the release schedule might vary from time to time.