Can I use different settings for the new documents created by Inkscape?
Yes. When you do File > New (Ctrl+N) or start a new Inkscape session, Inkscape loads the default template document which stores page format, grid and guide parameters, snapping and export settings, etc. It can even contain any pre-created objects. You can save any document as the default template by writing it to ~/.inkscape/templates/default.svg on Linux and [inkscape dir]/share/templates/default.svg on Windows. If you save it under any other name than default.svg in the same folder, it will appear in the File > New submenu but will not load automatically unless chosen. If you use a localized version of Inkscape, french for example, the document default.fr.svg will be used in place of default.svg. Thus you can adapt the document loaded by default to the user language.