17 Oct 2013
Curse is an enchantment type, not a creature type (or any other kind of subtype).
17 Oct 2013
The ability won’t trigger when a creature attacks a planeswalker controlled by the enchanted player.
17 Oct 2013
A Curse spell targets the player it will enchant like any other Aura spell, and a Curse stays on the battlefield like any other Aura. If the enchanted player gains protection from the Curse’s color (or any other characteristic the Curse has), the Curse will be put into its owner’s graveyard.
17 Oct 2013
The Curse subtype has no inherent rules meaning, but two cards in the Innistrad set (Bitterheart Witch and Witchbane Orb) refer to Curses.
17 Oct 2013
Each of the Curses can be attached to any player, including the player who cast the Curse.