Wildhoney is indeed one of the greatest metal albums ever produced. And that is just fact.
Hokay:
1) The first metal band I heard was Metallica, but the one that really got me into metal was probably Nightwish. Or Iced Earth.
2) Difficult one. I don't really have one single band. At any time it will be a toss-up between Agalloch, Falkenbach, Moonsorrow, Therion or... let's say Blind Guardian.
3) Same as above. Aforementioned Wildhoney by Tiamat is a definite contender. Kamelot's Black Halo. Blind Guardian's Nightfall in Middle Earth. Iced Earth's Horror Show. Therion's Lemuria/Sirius B. Opeth's Damnation (can that be classified as metal? yeah sure, why not). Shadow Gallery's Tyranny.