OK! Some news to issue 2) rtcWakeup:
The property
Code:
com.lab126.powerd rtcWakeup
can be set when the Kindle is in state
That means, 60 seconds after switching to screensaver, there comes the 5 second time window to set the wakeup property in seconds (how many seconds the suspend should last). I have to investigate, if it works also for a longer period like 24h with a reasonable accuracy... more to come...