Sending any number of 'Morphtronic' monsters from your hand to the GY is not a cost.
The ATK increase from the effect of "Gadget Hauler" lasts until it is removed from the field or flipped face-down.
If the effect of "Gadget Hauler" is activated while "Banisher of the Radiance" is face-up on the field, the 'Morphtronic' monsters are removed from play instead of being sent to the GY, and the ATK of "Gadget Hauler" does not increase.