Staff options for a small restaurant cafe business in France?

I am looking to open a small cafe later in the year with a business partner under the structure of a société par actions simplifiée (SAS). Both of us will be non-salaried employees. We intend to hire one staff member and would like to understand the costs of a part time employee.

The turnover will be low and expenses high so we are looking for opportunities available to us. Ideally we would like to have one staff member for 24 hours per week.

1. Is there an opportunity to hire staff through a hospitality school looking for work experience? I understand there is no free work experience but are there some benefits to an employer that goes through this channel?
2. Our business will not enable us to have an employee on a long term basis or a fixed contract scenario. I believe there a business is allowed three different non-fixed contracts before it must start employing on a long term basis. Can you confirm this?
3. Are there allowances to hire employees on a short term basis over the summer? And is this separate to the above?
4. We would like to have our husbands work in the cafe from time to time. Is there a way that this can take place without having to pay social charges/wages?

I would be grateful to learn of any other opportunities we’re not currently aware of for how we can accommodate a staff member into our business plan.