Plasterer - the implications of it being a regulated trade?

In a previous question I asked about my husband setting up as a plasterer here in France. Based on your responses you mentioned that plastering is a regulated trade and as such he would need to evidence either 3 years experience or a qualification. Despite having done the job before a number of years ago, he hasn’t yet had 3 continuous years working as a plasterer with self assessment records to support that timescale. He does have NVQ qualifications.

1. What do the authorities ask to see? Do they want to physically see that level of documentation before issuing his siret number or is it something they follow up with afterwards? What are the timelines involved do you know? He currently has his own website along with verifiable feedback from numerous customers to prove he is genuine and his work is of a good standard.
2. Are trades such as gardener or maintenance / odd job man also classed as a regulated trades and do they also need to have supporting evidence provided of 3 years experience or a qualification?
3. I asked about the less than or greater than 50% annual income clause - in what kind of typical scenario would this point be relevant to consider and what would the implications be?