Yes you can use it on the gas stove or in the fire. However, just becareful the handle does not get too hot that you will get burned when you pick the handle up. Also in a fire the outside of the Ecobilly will blacken like any other billy but is easily cleaned. Another way of boiling the water is to find a a shallow stainless steel dish (look in Op shops) that fits within and underneath the Ecobilly. In this dish you could use a thin layer of methylated spirits (use extreme care) to heat the billy. This is useful if camping and you cannot find dry eucalypt leaves and twigs. Alternateively, fire lighters could be used in wet weather.

You can, but you might be better off with a wind proof trangi that runs on the smell of an oily rag tiny metho burner (or gas). Very efficient and takes up very little space because everything packs into itself. And you will have 3-4 cuppas in 3-4 minutes. Mine lives in the car with small pots of coffee, tea, sugar and those tiny UHT milk packs. The Ghilly (this style of twig burner) are good for fishing when you are near water and also wood/leaves/twigs or you want to just chuck in a water bottle and nothing else. They are large and do not hold a lot of water, but do heat up fast (when you have no gas or metho). Originally used by the Irish game keepers out on the estates in very cold windy weather, and poachers, because the chimney design not only heats fast, but makes little smoke. DO NOT USE A TRAY OF METHO, it's dangerous in my opinion and can overheat and possibly BOIL OVER as metho does when overheated, which can spill out (alight and on fire) from underneath and start a bushfire. Alcohol burners need space around them to used safely. Never ever use them in a confined space like the ghilly burners.