Gas in the cold:
Use a remote canister stove with a preheat loop in the flame, and run the stove with the canister upside down to feed liquid gas.
You only need to run with the canister upright for long enough to get the preheat loop warm, and once you invert the canister you are no longer burning the propane part of the gas mix in preference to the butane part. You thus have good pressure both down to -15 (ish), and until the end of the canister.
If you use a gas stove with the canister upright, you are burning the propane part of the gas mix faster than the butane, with the result that there's no propane left by the time you are much over half used. After this you've no option but to warm the canister before trying to light the stove, and to keep the canister warm in use by using either a bit of copper wire to conduct the heat down, or a close fitting windshield that reflects the heat back down. Generally, upright canisters are best restricted to warm weather (> 15°).
Back on topic, fire steel thingys do work well once you've got the knack. I just lit a cotton wool ball, just to see if I still could. For the gas stove, an ciggy lighter is generally easier, even if it's run out and I'm just using its flint.
