Yes, they do exists high school at least they did in my high school. Alot of time the lines between them can be strong and people really try to enforce them but I wouldn't worry about it to much because if you are an outgoing person then you really will be able to move in-between the cliques and just form your own social group.
No one over the age of 57 does, and yes, they exist. They always exist, but you won't be protected once you go to work or off to school.
What do you mean not a typical high school?