Initial Research Questions EIRL EURL SARL SAS

Bonjour Valérie

I am very excited to have your support and i will have thousands of questions so i guess i will jump right in.

I am South African and my wife is French. We were married in France with a contract, after which i relocated to Paris.
I have spent the last few years following the immigration process, learning the language and simply enjoying France and have just received the 10 year residency card.

I am a beauty photographer and looking to re-open my studio here in Paris. I shoot both limited and unlimited prints and target both consumers and businesses.

Question 1. Legal Structure?

I have always run as a limited company and will be looking to do the same here, however i am not sure which format to register? EIRL/EURL/SARL/SAS ?
I have always started the business alone but have added business partners for various specialty reasons. I would like to keep this possibility open from the start, (meaning no complex restructuring/reclassifying later if possible)
I have previously used shares and dividends as an employee rewards system, however i don’t see myself employing additional photographers for at least 24 - 36 months.
I will however immediately need a hair and make up artist. My process has always been to trail 5 to 10 different people on multiple jobs before offering any sort of employment contract.
I like dealing with freelancers, those registered as micro entrepreneurs and those who are not. (example: i would pay the wife’s, cousin’s daughter who is at university and writes the copy for my marketing)
When dealing with other businesses, i always attempt to exchange services and or referrals as payment.

The business does not have very high startup costs but marketing can run up a decent sized budget. I have always used a paid referral system ( both businesses and individuals) and would like this to be easily available. 
I don’t initially need to draw a monthly salary for myself and can run this way up to 36-48 months. Yearly dividends however would be nice
If however for legal/accounting reasons i need to draw some salary it will be the absolute min requirement.

Question 2. Which regulatory body do i register with?

Question 3. Tax/Social/Mutual

As far as i know, my social contributions and mutual are covered between my wife’s salary and her employer. Is it possible to continue this way in the early stages of the business?
I am currently registered with the tax authority under my wife’s registration, (i am not exactly sure how it works) and ideally i don’t want the mix the business and personal tax. What is the potential impact ? 

Question 4. If my wife becomes a minor shareholder, +- 7-8% does this affect her tax and or employment? Would she have to declare anything to her employer?

Question 5. The business call service listed on your site? Is it included in the initial 120 or is there an extra charge. If so what is the amount?

I am sure you can tell that i am in the very early planning stages so there will be a lot more questions as i get my thoughts down on paper.

Thanks for everything