So from what I understand.

The openHAB bindings are used when you connect via the ethernet or serial gw. The bindings does some auto things like node id assign etc.

It does not look like people use the bindings when they integrate via MQTT. So you do not get the auto features from the bindings? Is this correct?

For the ethernet type the following is the config:

mysensors:type=ethernet
mysensors:host=<host ip>
mysensors:port=5003

What is the config for mqtt?

mysensors:type=mqtt?

How do you set the pub and sub?