Newbie Zwave question

Just got a USB for my HASS on RPI. I was able to exclude a few light switch and a thermostat from smartthings and add them to hass.

But I am curious at how to manage all the z-wave devices.
Is OpenZwave control panel needed any longer
what is the purpose of the
zwave_device_config.yaml and zwcfg_xxxxx.xml file

vs going through the hass front end to the zwave settings.

what is zwscene.xml

is the open zwave control panel still available, do I need it should I use it.
I have another thermostat, some door contacts , and a few more lights and switch to add.

Just trying to get a handle on managing all of it.