Chambres d’Hôtes business as auto-entrepreneur?

My husband and I opened a chambres d’hôtes last summer and we managed a turnover in 2012 of €7,000. Our main source of income is my husband’s private company pension from the UK which was declared on our first tax return last June. The sum we made from lettings should, as I understand, be declared as BIC on our tax form this year. And this will have a deduction of 71%, leaving 29% as net income, thus €2,030, is that correct?

We have no idea what our income from the chambres d’hôtes will be this year, but am wondering if we should register online as an auto-entrepreneur? If we did, I believe it should only be in my name as I do not have any other income. We are both exempt from social charges on income until January 2014, by way of our S1 form given to us by UK health authority.

So what I would like to find out is should I stay as we are as long as we don’t exceed the turnover level of €16,510, net income of €4,788, so as not to pay the social charges? Below this turnover, is it correct you do not need to register your business commercially or indeed register with the RSI? Or should I go ahead and register as an auto-entrepreneur in the hope that we may exceed that turnover, if not this year, hopefully by 2014? Does it matter at what point you register as an auto-entrepreneur?