i have many points to bring up:
1. If we go by what we have discovered in GoO and assume that Onyx was the prototype for the Ark then it is what is known as a Dyson Sphere, its a manipulation of space, its a machine that can take the size of one object and make its interior space multiple times larger.
and easy explination would be this, blow up a balloon, the balloon is much smaller then you are, the surface area of the balloon probably would even cover your whole chest, but now imagine that if you were to go inside the balloon and the inside of the balloon was the size of your house. outside its still about as big as your head, inside its large enough to fit a small petting zoo, your body has not changed sizes, it has just manipulatied space (not space as in outspace, space is in all the area around you) to reshape it into an area larger then it was originally.
More info can be found here: (its really quite interesting)
http://en.wikipedia.org/wiki/Dyson_sphere
http://www.nada.kth.se/~asa/dysonFAQ.html
2. The Rings do not distroy all life, they only distroy all life with sufficient body mass, plants, bugs, bacterium, and the like are not effected and therefore continue to live life normally. therefore the Flood will be uneffected as a bacterium, but without sufficient food it will die off everywhere except for on the rings becuase that is where it is created.