The whole thing is an evolution. There isn't really a starting point. Only a point where you think the elements all came together, and that's a matter of interpretation. Personally, I'd probably go with You Really Got Me, though plenty will come along and say "bah, that's not metal!"
No, but that's a good call. There are others like that, too, from "Helter Skelter" to "21st Century Schizoid Man".
By the way, wrong thread for this, but I just got reintroduced to the Kinks; from about 1970 through "Word of Mouth" there are few catalogues that can compete with what Ray Davies did. Opera, rock, metal, pop, folk, social commentary, not social commentary... really, really genius stuff.