If CEC is working then Kodi should have automatically switched from adjusting the volume internally to sending CEC commands. There may be some setting that needs to be adjusted on your TV or in Kodi via settings>system>input>peripherals>CEC adapter> although i’m not sure what that would be.
As for the home button and power control you can do that but in order to enable it to be sent you have to set in Kodi’s CEC settings (the location listed above)…
enabled> (on)
switch source to this device on startup> (on)
devices to power on during startup> (TV)
devices to power off during shutdown> (TV)
make sure to click “OK” after editing your settings as pressing the return button will exit without saving. You must also reboot.
The way the keymap is configured currently to power on you may have to press home two or three times depending as the first button press just wakes from the screensaver and ignores the mapping and a third press would be needed if you were not on the home screen where the action is mapped to. I think the Vero should normally turn on with the first button press (as it has a separate wakeup as part of its sleep function) in stock config but i’m not 100% on that as I don’t have a Vero with working CEC and I know they have been working on some changes to that feature lately. On my RPi I have to press it twice normally.
To power off the home long-press is only on the home screen so you would normally press home once or twice to get there and then hold down the home button and your TV should turn off.
You can find out more info about how the remote is configured here…