The same reason why Americans speak american...... LOL SILLY QUESTION
French
no
So that you can talk to french people.
French is the National Language so use French Terms!
People who speak fluent French are often referred to as francophones.
If you talk with French people and stay a long time, sure ! :)
to talk is 'parler' in French.
The best way to improve "your" french is to be with french speaking people and to force yourself to talk french. Listen to french tv, read books in french. I could talk in spanish but what made me really talk in spanish was to go to Spain and be 100 % into spanish (friends, TV, news papers, everyday life).
a lot of fancy restaurants have french named food, you can talk to people, and french sounds quite good when you speak it properly...
J'aime bien quand les gens parlent en français
No, unless if they happened to study it at school, of course.
to talk (verb) is 'parler' in French. A talk (noun) is 'une discussion'.