IT'S ALL FRENCH TO ME II

The following phrases are English translation from French. Can you supply the original French phrases - which are often themselves used in conversational English?

1. Pen name
2. Dance for two - as in ballet
3. Done deal
4. Joy of life
5. Please
6. Do or spend whatever you want
7. Purpose for being
8. Polished and urbane in social behavior
9. Head-to-head
10.One who recently came into money
11. "Allow to do" - minimal government interference
12. Responsibility of privileged people to act generously toward those less privileged

Answers:

1. Nom de plume
2. Pas de deux
3. Fait accompli
4. Joie de vivre
5. S'il vous plait
6. Carte blanche 
7. Raison d'etre
8. Savoir-faire
9. Tete-a-tete
10. Nouveau riche
11. Laissez-faire
12. Noblesse oblige