2. Heirlooming does NOT effect upkeep cost
edited OP to make this clearer, you guys seemed to not understand. if the hierloom is more or less base price, who cares?
anyway I asked paul/urist for heirloom info and he said: "Heirloom modifiers will probably change."
but after looking at game files I think what damage it says an item is ingame or onsite might be fairly innaccurate anyway.