User blog comment:TUSF/Light Novel Chronology/@comment-70.53.116.171-20170326163119/@comment-28251580-20170330071448

Progressive is still being written, though one book a year didn't happen with the latest book. Progressive 4 is available, but Progressive 5, which under usual release schedule was intended for December 2016, will be released sometime in 2017 in Japan. You may want to check Sword Art Online Light Novel Main Page, it has the release dates we know for JP and EN publishers.

For the other questions you may want to start a topic in the forums, since they have nothing to do with this article.