I just got an Insignia NS-BK1TSS6 kegerator and there is an extra white ring ziptied to it. There is a ring already on the high side of the regulator. I am correct that this ring is extra and not needed? The instructions don't say anything about it.
You should change the gasket every time you change the tank, (so I've heard).
In reality, I've changed the gasket every time I've misplaced it, which is probably two or three times. At less than a dollar per gasket, it certainly doesn't hurt much to change it every tank swap.