10/1/2009: You may ignore a Trap's alternative cost condition and simply cast it for its normal mana cost. This is true even if its alternative cost condition has been met.
10/1/2009: Casting a Trap by paying its alternative cost doesn't change its mana cost or converted mana cost. The only difference is the cost you actually pay.
10/1/2009: Effects that increase or reduce the cost to cast a Trap will apply to whichever cost you chose to pay.
10/1/2009: The number of targets must be at least 1 and at most 5. You divide the damage as you cast Arrow Volley Trap, not as it resolves. Each target must be assigned at least 1 damage.