I would honestly believe either, that the Circle lives at Castle Black or somewhere else in Morrolan's fief. And LOL. Teleportation really means you don't even have to see the places in between if you don't want to, huh?

That's an interesting thought about the succession. It does add some additional uncertainty, but then again, succession uncertainty is sort of inherent in pretty much all the inheritance style governments. So many declared heirs that didn't work out for various reasons...But yeah, it's almost certainly Dragon next. And judging from Soffta and such, the Jhereg (despite being a mob organization) still do attempt to participate in the legitimate power channels like being at the palace, and try hard to not get in its way or call attention to their illegal activity.