Courage for beginners confusion

In the book courage for beginners there is a bunch of twist and turns the thing that confuses me. When Mysti enters 7th grade out of no where her bestfriend Anibal is a hipster. I don't understand how out of no where she is a hipster. How did she decide she wanted to be a hipster. Also mama has a fear of going outside. The thing that I don't get is that how did mama get it? Has she always had it? How did she go to school? In the book it says, "I came to understand that mama had something called agoraphobia." Agoraphobic is what it is called when you are scared to go outside or be in public places. These are the only confusing parts in the book that I don't understand.