No, it doesn't. I'm reading the translation off Bulbapedia and while I can see how you can interpret it that way, there isn't anything directly saying that it's the fifth generation. You can't really say it's confirmed when so far we have roundabout phrases and speculation based off a number of clues. It's possible, perhaps even likely that it's the fifth generation, but it has not been 100% confirmed.
New Pokemon doesn't mean gen 5 though. Pokemon XD was a same-gen game and had new Pokemon as well.... as cameos. New main series game - what if Game Freak decide to make a 2nd series that differs from the main series somewhat, or is still a 4th gen game with a new region if they want to pad out the DS and wait for the next handheld console for a new gen? Patterns are made to be broken after all (and either way a pattern of some sort is borken - gap between gens, or the gap between a new Pokemon confirmed and a new gen game). Unlikely but possible. Let's not jump up and down just yet - likely its a 5th gen, but as I said disappointment has been had before. =P After all if you don't get overly excited, it makes the actual confirmation more fun arguably, and means a disappointment won't affect one so much.
Nah, that I doubt. HG/SS is already basically a Crystal remake anyway, as it has the stuff Crystal had that GS didn't.
I'd be iffy on new types - the system is already more or less steady as it is, for one, and if a new type came along that would require reworking stuff like Hidden Power and the such... and maybe would mean 4th gen would not be compatible with the 5th gen, ala 2nd and 3rd gen as 3rd gen had to change up the mechanics. (Assuming it's a 5th gen game of course, but IMO if not now it'll happen sooner or later anyway).
