Sure, Amir experiences significant change. This could be seen in his attitude, behavior, and outlook on various aspects. His growth is a key part of the story's resolution.
I haven't come across any reports stating that Jake Tapper is penning a novel. His focus seems to be on his journalistic endeavors, such as reporting the news, conducting interviews, and providing analysis. However, it's not impossible for him to venture into novel - writing in the future, but for now, there's no indication of it.