It's hard to say for sure without reading it, but likely Aang would still be a main character. He might be older and facing new challenges. Katara could also be a main character, perhaps with her waterbending skills being even more refined. Zuko too, as he continues to deal with the Fire Nation's future.
One interesting concept could be new bending techniques. Maybe the fanfic explores an advanced form of waterbending that combines with spirit energy. Another concept might be the introduction of new characters who have unique relationships with the existing ones. For example, a new airbender who has a different philosophy about peace compared to Aang.
It's a cartoon. Anime typically comes from Japan and has certain specific traits that Avatar The Last Airbender doesn't possess. This show has its own unique charm as a Western cartoon.
Avatar The Last Airbender is typically classified as a cartoon. It has distinct elements such as its animation style, story themes, and the way it's produced that set it apart from traditional anime.
Well, without having read it specifically, I can only guess. But generally in the Airbender world, it's a place full of elemental powers. So this novel might tell the story of the last airbender's struggle. It could be about their fight against the forces that are disrupting the balance in the world. They might be on a quest to find other airbenders who might still be alive, or to master all the airbending skills to become a true savior of their world.