Hello, I'm a Parisian living in Paris and a professional photographer. There's no problem in taking pictures. There are so many people taking pictures in Paris, since it's the most visited town in the world (14.8 milion international visitors per annum). About tripod, there are areas where you won't be allowed to use one unless you can show an official agreement from the City of Paris. For instance, inside the Louvre area, in public parks. If you need more information, send me a personal message.