Kosher in Paris
If you wander down the rue des Rosiers in the Marais, you will encounter a number of Kosher places. There's a deli, the name of which escapes me right now, that is popular and well known. When we passed by and looked in the windows, the cleanliness and food storage (trays of "crusty" chopped liver and egg salad) made the place very unappetizing. We passed. L'As du Falafel was a very good - and filling - lunch stop. Not sure whether it's kosher, but vegetarian falafels and plates are served, or prepared for take away. You'll know it by the crowds lining up out the door. The kosher bakery a few doors down from there was very good (most tourists go for baguettes; we found good raisin challah). I also remember seeing a kosher pizza place. There's a Chabad in Paris; they may be able to give you specifics.
I know this is too late for you, but for future reference here are two websites that list the kosher restaurants in Paris. Many of those places in the Marais are Jewish (and delicious), but not kosher!
There's a falafel place called L'As Fellafel, which is kosher and fantastic. It's in the Marais, I forget the street. Also, Essen Bentch, run by Chabad, I think. Jo Goldenberg is NOT kosher.
The Consistoire, which is sort of an overseeing agency for French Jews, is very helpful with information about candlelighting, etc., and they speak some English.