I can provide additional information about the 6th verse: it is hard to translate because it contains some slang language from 1830-1930. Fred J.'s translation is pretty acurate.

Et je p'tit Jules était d'la tierce
qui soutient la gerce,
aussi l'adolescent,
voyant qu'elle marchait pantre,
d'un coup d'surin lui troua l'ventre,

- une tierce = a group of thugs
- une gerce = a women
- un pantre / un pente / un pante = a victim of thug

--> "la tierce qui soutient la gerce" : the thugs that support women trade = pimps (in French, a pimp can be translated as "un souteneur" : the one that supports)
--> "voyant qu'elle marchait pantre" : this is actually the original lyrics from Aristide Bruant (1900's) and Yves Montand changed it to " "voyant qu'elle marchait pas au pantre" , meaning "realizing she would not aim at the victim of thugs/ be a complice of thugs" = "she would not accept to be a prostitute"
..... by a hit of a blade pierced her belly

--> and the next line "Quand ils l'ont couché sur la planche," = "when they laid her down in her coffin"

Léa