Except you forget about the existence of great aunts and great uncles. Then, those aunts and uncles would be cousins. It makes more sense to group all cousins together, since they are all members of the same extended family, yes?
no, your great aunt/uncle is just that, nothing more. everything has a different name because each member is inherently different and has a different role to other individuals in the family tree.
The offspring of a great aunt or uncle is an aunt or uncle
don't confuse him. the offspring of a great aunt/uncle would be your second cousin and your parent's first cousin