The little cross pins (from what my limited understanding of French offers) are aluminum wires more or less which fit into internal indentations in the case.
I have seen brass cases with holes which one can insert a couple of toothpicks to hold an over shot card which acts similarly.

As for the percussion cap, I initially thought the same thing as Lancaster.
But, I wonder, is the anvil of the case integral with the tube and the varying rims simply hold the primer and the ignition accomplished through smaller holes as in the Berdan system?
If so, maybe the pressure is great enough to seal the percussion cap reducing or eliminating blow-by.
Very interesting concept though.