There is no fixed schedule. A Journal gets published if there is a sufficient number of articles. The flow of articles we had a few years ago has slowed, so the schedule is now irregular. We're open to receiving article contributions from the community, though.
Do we have someone authorized to whom the articles must be sent? If the community contributes we can have a good number of quality articles (as far as I think). [ December 11, 2008: Message edited by: Himanshu Gupta ]
We don't commission articles on specific topics. It generally works better if people write about something they care about. The previous Journals have covered a broad range of topics; maybe those can provide some inspiration.