The whole point is that those questions above cannot be answered ahead of time. The synthetic securities are so complex and intertwined that the risk cannot be safely calculated w.r.t. the amount of money being invested in them until after the fact.
Nobody can say if anyone is charging enough for insurance because nobody can quantify the risk accurately. Noone can say if the company has enough reserves because they we don't know how correlated that risk is or how large it is. If I'm shorting a stock I know exactly how much is at risk (within a reasonable margin of error), because these are complex contracts meant to balance out other complex contracts all with extremely high leverage any imbalance can spiral out of control. And any unexpected large change can destroy the entire financial system.
There are more degrees of freedom than can be well quantified in way something can go wrong.
It's not that people didn't think to ask and answer those questions above, it's that with the complexity of the system and the scale of money involved and leverage used they can't be answered with confidence. Only the appearance of confidence.