You have KugelSchaft.pk3/KugelSchaft/models/weapons/rifle/, but should be KugelSchaft.pk3/models/weapons/rifle/. Adding 'z-' in front of pk3 file name helps too sometimes. Also, Program Files/Tremulous is the basepath (try /fs_(tab) ).
All non-default .pk3s/mods/etc should be in homepath/base, or if mod specific, then in the right mod folder.