Well the only thing I can help you with is the two hole top! One goes to the pump and then from the pump to your gas tank. The other hole is for ventilation. The reason you see two fuel lines on it is for when your done fueling you take the tube that went from the pump to the gas tank and put it on the vent hole when your done. Then when its time for refuel you just take the one off the vent and put it back on the gas tank tube. Therefore you dont get any moisture in the fuel while flying that could get in there from the vent hole being open.