I spend one to two weeks each year in Paris. In the past twenty years, I have only had two problems when photographing. The first was when using a tripod at night in the Place de la Concorde. A police officer told me I couldn't use a tripod (I think). She was very nice about it. I nodded and took down the tripod. Not really a big deal. The second didn't directly involve me. My wife and I were on a food walk and one of the other participants was a very aggressive photographer. She got into peoples faces. One of the markets we visited had a number of booths run by African immigrants. The walk leader had told us that because of the sellers culture, they did not like being photographed. I photographed the stalls and asked permission before including a person in the shot. The other photographer got hassled. Frankly, she deserved it.

Go to Paris and have a great time.
Buy a museum pass to avoid lines.
Make reservations for the Eiffel Tower--or walk up to the first level. I'm 54 years old and did it last month without too much effort.
If you like the French trifecta (foie gras, duck ((breast, confit or in cassoulet)) and creme brulee) it doesn't get any better than Au Petit Sud Ouest, 46 Avenue de la Bourdannais in the 7th.