Note that a cron job will only do the... job if the device is never put to sleep (i.e., it needs to be tethered to a power source).
Otherwise, you're entering the rtc wakeup wasteland, so here be dragons...
That said...
1/ You can either parse the input event yourself, the Kindle does things in a roughly sane manner (i.e., Linux evdev).
Or you can rely on third-party tools to do the heavy lifting (i.e., evtest or evemu, which I just added to USBNetwork. The stock evtest might be good enough, depending on what you need it for).
3/ Not quite sure what you meanly that? The front light intensity, you mean? (In which case, there are lipc commands that I don't remember OTOH, check KOReader's kindle powerd module).
4/ Basically the invert of the two lipc commands you quoted
.
Note that the pillow thing doesn't necessarily work as well as you might want it to on newer FWs versions. See comments about that in KOreader's startup script.
5/ See my comments at the start of this post. Otherwise, I don't see what else might be Kindle-specific in this query?