Individually I would assume they might even talk about football-results or friendship-stuff if they found the time for it.Okay, so I'm making dialogue between Inquisitor's what kinds of things would they talk about/how would they go about it in manners of calling a conclave to order?
I would personally give you a very free reign there but suggest that you would look into the sort of dialogues that happens at a high-command and religious gatherings like conclaves at the Catholic church, but then again that's me. I mean most are after all a mixture between generals and religious fanatics. And that's just my personal advice nothing more.
I would on the other hand assume Eisenhorn, Ravenor or even the Inquisition Wars (even though how canon that is seems to vary from subject to subject) would have something to say about how it would go down. And if really serious I would look into the Siege of Vraks for clues as there is said to be a conclave there, but that might be everything that's said about the matter.