My daughter's Insight suffered the same - battery reported as OK but then dropped at an alarming rate over the next few hours. It appears that this is not uncommon for that pump - it stays at 100% for quite some time but once it starts to go below that you need to be careful as it goes down to 0 more quickly than you'd expect.
As for the three cartridges in three days, Roche put out a warning that the key-lock on the Insight doesn't work as well as it should and you can very easily deliver an unexpected, default, "quick bolus". The advice was to change the menu settings so this default value was as small as possible. Could this have been the cause of your hypo, you were giving yourself boluses whilst asleep?
PS - glad to hear that you're OK and that your family knew exactly how to sort you out