You present a fairly specific set of circumstances in your opening message here, but the website below contains a useful, relatively easy to follow, guide to taxation in France, in english, and might be a useful starting point:
.french-property.com/guides/france/finance-taxation/taxation/
Uh Oh! - "You are not allowed to post URLs until you have at least 10 posts"
True I am not a regular poster in here at all, maybe you can add the necessary standard prefix to the above line?!