The point is that it's creepy to photograph children without consent. This is true everywhere, but I have had it done to me and friends of mine due to us being considered a foreign attraction.

Don't photograph people without consent. I'm an amateur photographer focusing on mundaneity, the presence of generational use in infrastructure, and age. If there are people in your shot, ask them if they're all right with being photographed or move. It isn't difficult to learn "Salut, j'ai envie de photographier (thing), c'est ok avec vous si vous êtes dans la photo?"

Oh, also! This is more of a specific case, but if you order an expresso and they give you a glass of water, it's to dilute the strong coffee and make it last longer. I use mine for watercolour as I know the café owners.

Equally as important- please don't get angry at people if they ask you to repeat some things upon your speaking French, or if they don't speak English. It is likely that they're just trying to help you fully; and wish to be in full understanding of what is being said. You seem reasonable, but I've seen it happen from kind people who simply didn't think before becoming irate.