Pre register a company in France?

I noticed in a previous reply in the forum, that you suggested someone to pre-register the company.

1. How is this done, and can I then start to work officially while waiting for actual registration, if I do so? I intend to work from my home - and occupy a rather large room which is a former master bedroom. This room includes ensuite bathroom and dressing room.
2. Can I include the total area while calculating the floor area and calculating the office rent? It will be around 28% of the house area.
3. Do you have a link to a step by step instruction to creating a SARL (or an EURL)?
4. When you say at least 50%, it includes 50/50 also? In such a case I would theoretically not be a majority holder?
5. I am for now not planning to market the services of contract workers to French companies. Would it in your opinion still be a challenge to consider for the company that I would be offering companies outside France remote/distance workers? Their employment contract would anyway be with the Asian company and not the French company.
6. I will use my own car for client visits and meetings. How will I verify mileage done - do I need to maintain a mileage ledger?. Is a company car a better option, and are there restrictions on using a company car for private driving?