Good job building some support underneath. Because once this steel stuff in the floor bends, its really difficult to get it straight again.
To the glass in the door: I had something like that before. Its really hard to clean, and it wont stay clean for very long. You can try to rub it with steel whool, but carefully. Because whatever you do, don't break that glass. You cannot use normal window glass to replace it, and this fire resistant glass is expensive and hard to get.