I'm not sure what 'inceat' means in this context. If it was supposed to be 'incest', that is a very inappropriate and unethical topic, and it's not something that should be taught in that way. Maybe it's a miscommunication or a wrong word used.
One common theme could be friendship. Kiba and Hana might be depicted as having a strong bond of friendship that they develop through various adventures. Another theme could be growth, both as individuals and in their relationship. For example, they might learn important life lessons together.
Yes, there are likely some out there. You can start by looking on fanfiction platforms that have a wide range of non - adult works. Try searching for specific tags related to Kiba and Hana. For example, on some popular fanfiction websites, you can filter by genre and rating to find appropriate stories.
Well, it's hard to say for sure. The concept of 'porn-like' is quite subjective. Some might consider certain novels with excessive sexual descriptions as such, but it depends on individual perspectives and cultural standards.
In many places, 18+ porn comics are considered illegal. This is because they can have a negative impact on society and violate moral and legal standards.