I haven't read the books in a while, and yes their unnoticed existence is a stretch, but it is explained that they move frequently so people don't notice they haven't aged. They would not have stayed in Forks much longer. I'm pretty sure there is a part, maybe in the movies, where Bella sees all the many diplomas on the wall from how many times the Cullens graduated high school.
Their all being out of class when it is sunny is attributed to their father taking them camping every time the weather is nice I believe
Their all being out of class when it is sunny is attributed to their father taking them camping every time the weather is nice I believe