1. 200 bars and no less.We were using AL80s. My fills were anywhere from 2800 to 3200. I never heard anyone speak of steel tanks so I'm not sure. We didn't do our own testing (didn't bring our tester bc it needs a new sensor) but they put the % on a piece of masking tape on your tank. I don't remember it being more than 1% off from 32.
2. I had never used any nitrox tank without personally analyzed it.