I actually put in the sextant purely for the humor value, and yes, Jahura is right, we were too distant from the Vikings for them to be of any help, if I recall. Besides, they were busy trying to dig a canal for their longboat. Or something.
Anyway, regarding the cult: At one point, I considered that there might be a Nyrond plot operating in the background there, and that was how Tully got pulled into things. It was established way back that he would be away from the hotel for an indefinite period of time - years - on Nyrond "business" - which this might well have been. But as soon as he realized that the operation might run afoul of those he cared about, his own goal became to protect Marae and the hotel and its residents.
My thoughts on the plot was that it involved the cult in some fashion: for fun, profit, and possibly giving them (or someone through them) comeuppance, not necessarily in that order. Toz would know only what the cult wanted him to know, and that knowledge might or might not be accurate; it certainly would not be complete. But as for details, I have been at pretty much a total loss.
As to the exact nature of the plot, that would probably depend on which Nyrond engineered it, and Zander would have a far better idea than I about that. I was prepared to wing it, or if I couldn't figure it out well enough, drop it, but since Zander is now here (even if he has yet to find Now Here), I figure it won't hurt to lay all that information out there and see where it leads us.