Ans. 1) Although the double check is still needed, the answer would be "Yes".
Ans. 2) Unfortunately, there is not a simple way to check if the power supply voltage is getting higher than the release voltage.
One of solution could be to monitor the voltage externally.
Ans. 3) NO. the interrupt occurs only when the voltage drop happens.
Regarding Ans.1), confirmed that the interrupt occurs for this case.