our application is composed of several modules grouped in two packages, and one script.
I am not sure, and don't manage to google my way through to knowing if the modules need a coding directive in order to manage our native french accented strings, and while we're at it, a shabang with the interpreter directive, or if it is enough to put these two lines in the one script.
Scripts need shebangs. Modules don't need shebangs -- they're sometimes used to make text editors' jobs easier (in detecting the programming language easier), or if a module can be run as a script to execute its tests, but are not called for otherwise.
All Python code, whether in modules or scripts, should have encoding directives when not using the default encoding for the Python version targeted (ASCII for 2.x, Unicode for 3.x).
Do Python modules need shebangs or encoding directives?