Hello Laurent! I apologize for the delay in responding; life intervened. We are all volunteers here and do the best we can to keep up.
To answer your question, I think you are asking if you need professional training to be a personal chef. This forum is the New Users Introductions forum, so answers to specific questions such as this would be better answered in one of the topical forums. Since the one dealing with personal chefs is for professionals, and you are a home cook (as I am), that forum is open to you to read and explore- but not for posting. However you are encouraged to post questions on this topic in the general forums. I suggest you read and research first. Use the search tool here to do that exploring. Some of your questions may be answered by reading. Then, your further questions will be refined and well-focused so the professionals can answer them in the general forum. I suggest posting in the Food and Cooking forum. Start a new thread there with an appropriate title that will attract chefs to answer your query.
I encourage you to return here to introduce yourself and tell us a bit about your "culinary" self- what you enjoy cooking, how you became interested in food, etc. We look forward to your participation here and hope you will be enriched by being part of the community.