Look at the second picture on post 359. Look at the top left corner of hole, where a major piece of skin is bent upward. You have the green coloured aircraft skin, but inside of that, you can see the slightly darker coloured green, of an O2 bottle still in situ. Now the missing bottle/bottles and relevant supply pipework, would be where the hole is, moving forward to the front of the aircraft. I imagine that passengers may have trouble with their O2 supply, with quite a large percentage of the system missing. I do not suppose Boeing, when designing the system, built in fail safes for completely missing bottles within the system, which also by its very failure, possibly caused the decompression which the system was there to protect against!
As to starting the supply to the mask of each individual passenger and if the design has not changed from -200 days, you would pull the mask towards you and a length of cord attached to both the mask and a plastic pin in the oxygen drop down assembly supply manifold, would be removed, so allowing supply to the mask.