Answer:
Hard to catch, easy to hold. Can't be seen, unless it's cold
A house with two occupants, sometimes one, rarely three. Break the walls, eat the boarders, then throw away me.
With sharp edged wit and pointed poise. It can settle disputes without making a noise.
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
What is full of holes, but can still hold a lot of water?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.