On the questions above ... After many tracing, trial & error, I finally manage to get it working. Hopefully it will be of use to somebody in the future.
a) On the action level, do I need to specify an OBN object & OBN operation needed?
Answer: Yes!! You still need an OBN
b) Do I need to specify something in my PFCG profile?
Answer: Yes!! It still need to be specify as an OBN target!!!