French cafes and restaurants must display prices including tax and service. The useful traveller habit is to read the board before taking a seat, not to reconstruct the bill afterwards.
Menu is not the same as carte
The card is common, not compulsory for the merchant
Visa and Mastercard are widely useful, but a business may refuse cards or impose a visible minimum. This is why EUR 5, 10 and a few coins remain useful at bakeries, market stalls and small cafes even when the rest of the trip is contactless.
The free water phrase
When you are eating, ordinary tap water is included. Ask for une carafe d'eau, s'il vous plaît. Bottled mineral water is a separate product and can be added to the bill.
Prices should be readable before commitment
Restaurants must show menus and prices outside during service, and cafes must display common drinks with volume and prices. A terrace is not permission for a surprise price. Read the posted information and ask when seating options are priced differently.
Choose EUR at the ATM or terminal
If a machine offers your home currency, that is dynamic currency conversion. Choosing EUR normally lets your own card network and issuer handle the conversion. Read any operator fee before confirming.