Seems you have most bases covered, if you are on your third and forth renovation, you obviously are a professional/commercial renovator in which case you should employ professional tradesman to carry out the work you are going to sell on to clients with the indemnity of the professional ten year insurance required of any tradesman in France.
Professional /commercial, not at all, we had one house in Normandy which we renovated whilst living there ( 10 years ) then moved to the Correze , buying a complex of three houses together, we have finished one and are starting on the other two., again living in a building site. Unlike or like other expats we cannot afford to employ tradesmen especially whilst I have enough skills and energy to continue. This is more of a lifestyle and not a business, the business parts maybe will be having two houses for gite or rental.
If we sell it will be made clear that I renovated the properties ( there is always the possibilities of purchasing an insurance policy to cover the 10 year indemnity privately ) should that be required by the purchasers .
Although I posses skills I don,t profess to knowing everything and work on the principal that you are never to old to learn something new or to proud to take good advice , which is something that was instilled in me as an engineering apprentice and should be a mantra for all skilled people in any profession, hence me joining this forum.
Before renting we will have all the electrics professionally checked to satisfy the insurance company. Until then I will have to carry on as I do and of course will ask periodically for advice if I,m stuck. Thanks for your understanding.