I own an LS-WVL too. I just want to respond to Issue 2 of the OP. You can change the SHUTDOWNCMD to `shutdown -H +0` to prevent the NAS from rebooting, as with the default `shutdown -h +0` command. `shutdown -H` halts the NAS box; and if you run the command manually, you'll have to power cycle it in order for the power switch on the back of the NAS box to work again. However, in the case of a prolonged power outage, the UPS does it automatically for you.
Code
# cd /etc/default/
# cp -p openmediavault openmediavault.original
# echo 'OMV_NUT_UPSMON_SHUTDOWNCMD="/sbin/shutdown -H +0"' >> openmediavault
# monit restart omv-engined
# omv-mkconf nut
# systemctl restart nut-monitor