1. The personal air meter becomes visible as soon as you put on the emergency suit. If you haven't done that by the time area air runs out, you will die.
2. It's already mentioned that there are some emergency backup systems in Laurion that you simply can't turn off because they're considered essential. The air recycler (running at minimum power) is one of them.
3. I've planned to make the water recycler use power for a while now, but was always wary of making such a huge change to balance. I now have an automated balance tester, which should make it much easier to test that type of change without having to get people to play through it and get their opinions of how much easier/harder it makes the game.