Words marked with a star are allowed in Nynorsk. Making Norwegian dictionaries for word processors that doesn't have one, again with a sensible subset of words. Routines for the first three items on the above list is included in the Makefiles. The last three was too hard to implement in Make. You can also find dictionaries for a lot of languages there.
Older versions have a bug which shows up when searching dictionaries with non-English characters.
If you don't plan to have a Norwegian words file for lookup, you don't need to worry about the Look program. If you want to use ispell from Emacs, i recommend upgrading to the latest version of ispell.el . This version supports Norwegian, and it has become clean to include local dictionary definitions. It is almost like the version included in in Emacs-20.4. An old version is included in emacs-20.3, but you would like to have the new version with important speed improvements.