Les Chiens de Guerre

We've encountered an bit of a problem in out first Hell Dorado game. We're not sure how much damage is needed to kill a model.

Lets take the Two Headed Dog from the Égarés. He has 9 circles on his card. One with a skull and eight with the numbers 1 to 8. So, how much "live" does he got? Eight or nine? Does the skull count as a point of life or is he dead when I have crossed out the eight "numbered" circles?

The skull does not count toward maximum life points (actually, that's mean the skull equal 0 PV).
The highest number non-crossed out is the actual number of PV.

refer to number in the "red seal" to know how maximum PV a model has.

So, do you start out by crossing the right-most damage box, and then work your way to the left?  When you cross out the skull the model is dead?

Otherwise, models like the arquebusier who goes into wounded state on a "1" would never be wounded, right?  :)

yes, you start crossing out from right to left (to the skull, that's evidence)

when you cross out the "1"-circle, the character is dead.

A model is wounded when there are only green numbered circles left. An Arquebusier is wounded when he loses 3 HP, death when he loses 4.

In fact, the last damage box not crossed is the number of hit point of your character. Therefore, if 1 is the last box not crossed for the arquebusier, then he has 1 hit point ad he is wounded.
If the last not crossed box is the skull... then you're dead.