There is no official answer in English on the Web to the question "how to start a company in France", so we've built a website to guide you through it with as little headache as possible.
It's open-source software [3] built inside the French public startup incubator, beta.gouv.fr.
For those interested : does it convey most of the information you need ? What's missing ? It's the first iteration, and we're planning many new features.
[1]: Startup nation ? https://news.ycombinator.com/item?id=18066248
[2]: The French healtcare and pay as you go pension systems are also regularly discussed e.g. https://news.ycombinator.com/item?id=12998163
[3]: Source: https://github.com/betagouv/syso/