The wiki is both a useful and mandatory resource as the game doesn't hold your hand at all. Fortunately the game runs in a window so it's easy to tab back and forth as you come up with questions. The wiki is so expansive just about every question you can think of has an answer in there.
The amazing part to me is that they're still selling thousands of copies of the game per day. In internet terms Minecraft is a grizzled veteran and yet it still manages to hold people's attention. Mojang keeps a running tally on their website:
It's an important number too, as they've said they'll keep putting out updates for the game as long as it keeps selling.