Water Injection - Nos, Questions About Both Options

[nObOdy]

So im confused - i was reading some posts and i came across one that talked about how nos is completly flammable - well i was curious and i looked around in some more posts and it seems that a lot of people think Nos is flammable - but.. it isnt is it? it basically is oxygen that when heated to 565 degrees' it expands and creates an assload more oxygen and cools things down?

Also - I had heard of Water Injected Engines - well i was really curious as to what the heck that means - the last i heard of it was on a 3s-gte swap someone was doing and they found out thier version was water injected? What is that??
wouldnt you use antifreeze if it was used to keep temps down? ??

thanks in advance - sorry if this has been answered - i looked around for a while
nObOdy