The Module class has access to the parent workitem only. There it would be appropriate to add services that need to be accessible to other modules.
The module controller has access to the module's workitem and can add services (and other items) that should be local to the module (and its child workitems).
The three static methods you mention are empty. Methods that do not depend on the members of the class are often marked static to avoid the overhead of passing the instance reference. FxCop suggests this and ReSharper may do it automatically.
Bill J.