Since the release of Vivaldi 5.6, bookmarks' descriptions and nicknames are included in the import/export feature. Separators are also included, although the format hasn't been changed. If you'd wish for this to be changed, please start a new topic.
In the future, please post only one request per thread, as it makes it more difficult to maintain and follow up on requests asking for multiple features/changes in one post. Thank you! š