You can add batteries to the V2 hub so that it will work w/out power. Keep in mind your devices that you need to work when power is out also need to be battery powered or on UPS backup.
The new Lowes IRIS keypad works. It doens’t it’s device type is not local yet. But there has been some mention that SmartThing is working to provide official support for the new IRIS devices.
This has been requested many times, I would guess that it’s gonna come.