I specifically want to bring up that "villain character", so I might talk about the other stuff more later (although I will say that big guy with the shield is clearly a Moblin, meaning calling the other pig guys "Bokoblins" was not a mistake).
The character we see in the trailer who everyone keeps saying is the villain (even Vaati) is clearly the same character from the promotional artwork, who has been confirmed to be the spirit of the Skyward Sword. Just look:
Image from the trailer (provided by zeypher):
Skyward Sword from the promotional artwork:
See? There are design differences, yes, but it goes without saying that we'd have those considering the original image was conceptual, and didn't even match the style of the final game. Skyward's Sword's face has vague features, so the facial appearance of the trailer version isn't that surprising, really. If you also look to a different point in the trailer, near the end when he/she teleports away, you can see the legs have a similar diamond pattern. The biggest difference is the cloak, but it's not that big of a jump.
Now, despite feminine features the version in the trailer looks kinda male, but that's also not too strange considering Aonuma said this: