Hello! Sorry for the late reply - I haven't been around the site for a while :S
For the manga, the latest volume out is volume 9, and I think they are still coming out. I don't know when the next release date is however.
And as for the novels, after the main series ended, a new hardback book based on the stories after Ryuuki's ascend to the throne came out - this book dealt mainly with the history and after story of Yuushun, Anju, Ouki, Ryuuki, and Shuurei. And about a month ago, a fanbook also came out, including a drama CD, which was the last ever drama CD for Saiunkoku. Very sad