No, "artifact" is not considered a creature type in Magic: The Gathering. It is a separate card type that represents non-living objects or magical items in the game.
No, an artifact is not considered a creature type in Magic: The Gathering.
No, a creature is not considered a spell in Magic: The Gathering.
No, a planeswalker is not considered a creature in Magic: The Gathering.
Yes, artifact creatures are considered artifacts in the game of Magic: The Gathering.
Yes, artifact lands count as artifacts in Magic: The Gathering.
The most powerful monocolored creature in Magic: The Gathering is generally considered to be Emrakul, the Aeons Torn.
An Artifact Creature is simply a creature who is also an artifact. It is subject to all normal rules regarding both creatures and artifacts, and if a spell can be used against a creature or an artifact, it can be used on that creature.
Yes, artifact creatures are considered both creatures and artifacts in the game of Magic: The Gathering.
If a creature has Intimidate, when it attacks, it can only be blocked by creatures that share a colour with it, or artifact creatures.
Yes, creature tokens are considered creatures in Magic: The Gathering.
'Artifact' is a card type, not a creature type. You can't pick 'Artifact' for the purposes of Extinction. Most artifact creatures have a creature type too - construct, myr, etc, but if it doesn't, then it is technically immune to Extinction, like Morphs.
No, in Magic: The Gathering, you can only block one creature with one creature.