If a cost to cast a spell includes revealing a card, that card remains revealed from the time the spell is announced until the time it leaves the stack.

If Champion of the Clachan is countered or otherwise fails to resolve, the beheld card will remain in exile indefinitely.

If an effect refers to a "[subtype] card," it refers only to a card that has that subtype. For example, Glen Elendra's Answer creates a Faerie token and features a Faerie in its art, but it isn't a Faerie card.

If a card in your hand is already revealed (perhaps because it was revealed to pay a cost of a spell that's still on the stack or due to the effect of a card like Telepathy), you may reveal it again to pay the cost of another spell or ability that requires you to reveal a card from your hand.