Obviously I want to keep the amperage at its lowest for work on the mini but i don't know how to configure the rocker switches for this. Is it the low or high side of the switch that defines the setting? Anyone know?

(of the three white switches first is HIGH-LOW, second says MAX at the bottom, third says MED-MIN)
Its also using loads of gas. How long should one last or how much can you do with one of the little bottles?
Cheers