Thank you for a really detailed reply. It sounds like you are speaking from experience.
I am hoping to start a business, but it may take a while to get going. It will be mostly low key, so I'm not sure how much I will be paying in via taxes. My added complication is that my sister in law wants to move with us. She is disabled. I know that some of her benefits can move with her, but she cannot work. Do you think that she would be able to get her medications in France, or would the same rules apply to her? I reckon private medical insurance for her would be very expensive.