Well, about that.... 2. is actually Agartha, legend of the underground city=state located at the Earth's core. 3. I kind of deducted that the duel will take place in whether Fiji or Indonesia....just take a look at the 4 burning spot, you'll know what I''m talking about.
the main series consists of 3 alternate routes, all of which are considered canon: Fate/Stay Night, Unlimited Blade Works and Heaven's Feel. There's a prequel to all three of these, which is Fate/Zero. Fate/Zero and the three alternate path anime (FSN, UBW, HF) are the "main" series/parent stories. Others are mostly spin offs. (Heaven's Feel didn't get an anime yet, it's getting a movie later this year)
Woah! They are announcing so early? Huh, I wonder what the plot will hold. I wonder what will be the cause of the end this time. I also hope for a Tsukihime event this time. Still, I'm hyped!
Venom Heart people think we are going to resolve mysteries with holmes because the narrator speech sounds like his, Also the name of the chapters looks more like it than the previous, they give a more mysteriousish vibe. ANYWAY I'M HYPED