Questions About O. Henry's TRACKED TO DEATH (1)

I'm trying to translate a part of O. Henry's Tracked to Doom. The story takes place in Paris, so in the short novel there are many French which is beyond my knowledge. So I list them here and hope that you can help me explain these French sentences. Incidentally, there are also some questions not caused by French, I will also list here and hope that someone can explain them:

This is the link of the whole story: http://www.literaturecollection.com/a/o_henry/130/
I think that based on you knowledge about English and French, many of the problems can be solved without taking the trouble to locate them in the specific context. Most of them are at the lexical level.

1. At the beginning of the story, what does "tis" mean? "It is"?
2. Does "Convent Notadam" mean the Cathedral of Notre Dame?
3. "Hundreds of fiacres drive madly through the streets conveying women, flashing with jewels and as beautiful as dreams, from opera and concert, and the little bijou supper rooms of the Café Tout le Temps are filled with laughing groups..." Here, what does "from opera and concert" mean? It means that these women are going to operas and concerts or they are leaving operas and concerts?
4. "The first scene of our story is a cellar beneath the Rue de Peychaud." Here, what's the "cellar"? A kind of bar underground? I cannot say that it is a restaurant right?

Here comes the questions about French:
5. "'Voila, Gray Wolf,' cries Couteau, the bartender. 'How many victims
to-day? There is no blood upon your hands. Has the Gray Wolf forgotten
how to bite?'
'Sacre Bleu, Mille Tonnerre, by George,'hisses the Gray Wolf. 'Monsieur
Couteau, you are bold indeed to speak to me thus.
'By Ventre St. Gris! I have not even dined to-day. Spoils indeed. There
is no living in Paris now. But one rich American have I garroted in a
fortnight..."
In the second paragraph of this part, what does 'Sacre Bleu, Mille Tonnerre, by George,' mean? All people's names? They are killed by Gray Wolf? Why "by" George?
and in the third paragraph what does "spoils indeed" mean? I also couldn't understand the last sentence "But one rich American have I garroted in a
fortnight..."
6. "Que voulez vous?
Avez-vous le beau cheval de mon frère, oule joli chien de votre père?" A long French sentence. I can't understand it.
7. "Tout le monde, carte blanche enbonpoint sauve que peut entre nous revenez nous a nous moutons!" The same as the previous one.

Im sorry that there are too many questions. Thank you very much for your help!