No, I don't think booking a hotel would be good. And not in France btw, because that's not my final destination. I think I'm travelling with my simple letter, and in case they complain I'm just going to say I'm following the Swiss norms, which is the truth, but I think they probably won't give me a hard time because of it, they can just call my friend in case and ask anything they want. Besides, I got the other requirements, such as money and return ticket, so I think I'm alright...Thanks everybody.