Hi ogergo, some quick answer. Would love to go deeper but I have not much available energy for this right now. 

"The Facilitator may test the validity of a Proposal by asking questions of the Proposer."

In wich steps may the Facilitator do it?  I suppose the Objection round and the integration round... Any CCM may request the F to ask it?

Personally I use the "Clarifying Questions" step to ask several questions like:

• what's the tension behind the proposal?

• could you present an actual, specific, and reasonable example situation?

• the tension comes from/limits which one of your roles?

Any CCM may request the F to ask it?

Not specified, in the constitution. As a CCM I would ask myself the same 3 questions as before during the Clarifying Questions, state this is not a valid proposal in my reaction if I think so, object as Non Valid Governance, and show up in the integration step if needed.

Hope this helps,

Bernard Marie