So it *is* Tolkien's work, just not Tolkien's work that we can see in a book

Ah, I see, but unfortunately it doesn't make the little pictures on the map of Valinor any clearer.

I've used the Celegorm and Curufin saying they would go after Thingol thing in a fic.

The Teleri did attack first - by pushing the Noldor into the sea. It doesn't say Turgon participated in the Kinslaying in the Silm (whereas it actually says that Fingon did), but then again it doesn't say he didn't.

I think it's a very reasonable argument that Turgon thought that the Feanorians were improving and got a nasty shock when they attacked Doriath.