On the question of who to protect, I'm thinking twothree might be important. If he can detect Chaos activity, he may also be able to find them before they strike.
I'm going to keep my eye on SirFozzie. The Inquisitor General of Ordo Hereticus would be a perfect place for an infiltrator to land....plus I've still got a grudge against him for (rightly) knocking me out of an earlier game.