These are great ideas and could work well given that there are enough participants and that those are comfortable enough with one another to share their work/ideas in this way. An “unconference” may work well as an add on to some primary event. The problem I see with an unconference is a perceived lack of focus or purpose. We may need some minimal structure to get things going, but don’t want so much structure that it shuts everything else down.
You mentioned rubrics. One focus could be on critical inquiry – How do rubrics hinder teaching and learning? for instance, Or, in what ways are learning objectives harmful to learners? Again, both questions are about constraining structures so might fit in well with the premise of an unconference.
Personally, I am a little impatient with much of the “training” bent of a lot of faculty development activity. All this training is rooted in the premise that this or that method, technique, process is useful and valuable, while in many cases there is no evidence to support such assertions. People are just doing what everyone else does. If enough people do it, it is called “Best Practice”. Good grief!