The Importer only imports from Opera Presto to the New Opera. They are currently at work on being able to import from third party browsers. For the time being you can work around that -- import into Opera Presto first, and then have the Importer move bookmarks from Presto to the new Opera.
As for a Bookmark Manager, you can get them via extension -- like Chrookmarks for Chrome or Neater Bookmarks.
What are you trying to do?