Re: why anal and oral are an exeption?
sorry LKC bhai but I think although indirectly, but it is somewhat related. Anal sex is a trademark of homosexuality in men specifically.
So yes that is why Islam prohibited it so much as it is an un-natural act maybe in some limited case performed by animals. Otherwise it is not even done by animals. (I am referring to the report that was on BBC saying animals do it etc.)