There is a whole thread here you can search for answers.
Not sure that's right. TL;DR: you can set up groups of devices that check different things (battery level and last activity being two of them), and a device can be in multiple groups.
DAC doesn't depend on events, it looks at state whenever you trigger a report.
A report can be set up to be triggered once a day, or you could set it up to trigger a report every time a (typically virtual) switch is flipped. For instance, @ilkeraktuna , your rule above could flip such a switch and if DAC is set up to trigger a report on it, it can send out a notification.
Agreed - I change the AA alkaline batteries on my locks when they reach 50% or 6 months, and then use the remaining charge in other less critical devices.