I'd like that to be added to C320WS as well. The stock sounds are not great.

There should be offline notifications for all devices

If you use the original power supply, I don't see anything wrong that could happen. Just don't mix up the cables. I use an adapter like that and it works great.

This should be implemented in all cameras.

Would be useful

You should be able to do that by using the same account on both devices. Honestly I wouldn't use the home/away from home feature anyway because the those settings don't sync up on other devices, so...