Yes. Her stories are important. They carry the history of the Avatar world. They can teach the younger generation about the past battles and how they overcame difficulties.
Yes, in some of the visual novels, there are hints at new or modified bending techniques. For example, in certain story arcs, characters might combine different types of bending in unique ways, like using water bending to enhance earth bending in a specific situation. But it's not like there are completely new types of bending out of the blue.
She might tell stories about her adventures as an earthbender. For example, her experiences fighting against the Fire Nation and how she used her unique earthbending skills to overcome challenges.
Yes, there are many non - adult fanfics about Toph. You can find them on various fanfic platforms. Some might focus on her adventures, her friendships, or her growth as an earthbender. For example, there could be stories about her training new earthbenders or her interactions with the rest of the Gaang in different scenarios that don't involve any inappropriate content.
In some fanfics, Toph has to face off against a new breed of earthbenders who use a different style of bending that challenges her traditional ways. This forces her to adapt and grow. Another plotline could be Toph getting lost in a spirit world - like realm where the rules of bending are different, and she has to find her way back while also learning new things about herself and her powers.
One plot idea could be that the OC is a new earthbender in town. Toph senses their potential and decides to train them. Along the way, they face challenges like a group of earthbenders who don't want an outsider learning their ways. Another could be the OC is from a different nation but has an affinity for earthbending. Toph helps them hide this from others while also teaching them. Or perhaps the OC has a special ability related to earthbending that Toph is intrigued by and they go on a journey to discover the origin of this ability.