"....growing from the size of a marble to a volume larger than all of observable space in less than a trillion-trillionth of a second."
Doesn't that break the "speed limit"?
The space itself has no mass, so it's not subject to the "limit."
No, things traveling through space are restricted to the speed of light. Space itself can go as fast as it wants.
It's not really accurate to say that the universe expanded at speed xyz, its more accurate to say that two points on the surface of the 'marble' had extra space put between them so that it appears that they are receeding at that speed.
I suppose it is theorized that C did not get established as a property of radiant energy until after this "expansion" business.