Formalizing skills learnt on the job as an artisan & pros/cons of moving from Micro entrepreneur to EURL

I´m an autoentreprenur underatking small building jobs – petite bricolage – registered with chambre de métier, under regime fiscal – microentrepreneur. My skills were learned on the job, I don´t have a professional certificate hence when registering in 2020 I was advised to use the broadest APE code.  This is now proving to be an issue because, over the last few years, I developed new skills which enabled me to take on much bigger jobs for which I need to have an insurance ( liability, warranty). I can not get an insurance without supporting evidence that I have qualifications to do the job.

1. How do I go about formalizing my skills developed on the job? How long do I have to work to be able to show that I am qualified to do the job? Is it three years?

2. It is my understanding that when I reach the VAT threshold for providing services, which is just over 36,000 EUR a year, I will have to register for VAT. How would that work with my current regime fiscal? Will I be able to claim VAT on the cost?

3. Would it be more beneficial at that stage to change from Microentrepreneur to EURL? What will be the advantage of that? What will be the associated cost?

4. I don´t employ staff but I work sometimes with other artisans and we split big jobs and invoices separately. Is there a way to create a cooperative for the specific job? How does it work? I don’t have many overhead costs ( other than fuel, wear and tear of the car, insurance, telephone and tools).

I hope all the above makes sense and you can help.

Best Regards,
Dan