I am using this addon for koidi https://github.com/Paulemann/service.shutdown.watchdog which should address most or at least some of your requirements.
In kodi you must configure a keymaps.xml (or any other .xml) file in userdata/keymaps with the code of k400r power button to trigger the script.
I am not yet sure why you're taking all the effort to have vdr shutdown separately. I just shutdown from kodi and that's all it needs.
You can configure wakeup timer via a small exceutable script setwakeup.sh you put e.g. in /usr/local/bin and which is specified under kodi pvr & tv settings -> energy savings -> wakeup command: sudo setwakeup.sh