I searched the forums with "Language" and came accross a post about support for Chinese. It mentioned searching the Wiki (of course) and there I found the page for WP L10N (localization) page.
Check the <b>1.2 WordPressPOT</b> section, among the language files there is french and also a link to an example site in french. While checking that out I found a couple of small problems in his translation and contacted him.
About the first day of the week, can you be more specific ? There seemed to be a bug about it, check this message:
First day of the week?
Once you're done, come back and let everyone know :)