What kind of business registration for a consultant in France?

I work as a freelance product design consultant. After spending last summer in the Alps, my wife and I decided to stay and live in France. Due to this, my circumstances have changed somewhat and I need some help in setting up a new business model i France. My business was registered in the UK before, but we are now officially classed as non UK residents - after spending 8 months in Vietnam, before arriving in France in June 2010. I was classed as a sole trader in the UK. My wife is now working in Geneva and has been able to register all her details and health cover with her new company.

My goals are to continue with my freelance consultancy business based here in France, with a view to expanding; initially using other external freelancers and eventually a design studio with staff. Therefore I am seeking advice as to the best possible options I have in France or re-registering as a UK resident with a home abroad etc. If this is even possible/a viable or better option? I have seen there are numerous options as how to and what to register as, based on profession etc. and would be grateful if you could help me understand the best options for myself? As an Individual working within my own design consultancy business but looking to grow. I will be setting up a new company name and website also. Turnover I expect 35,000 euros and expenses around 5,000 euros.

I have one main customer based in France and a few others in Europe. What kind of business registration is the best option for me? What sort of tax will I be paying on my income Also how and when will I be able to register for healthcare and social benefits in this country?