I just started reading dark heresy 2nd edition while i have some experience with WoD i have none with their adventures but i do like the nurgle route as the clean or even the drunken livers could even be used as a "pharmaceutical" testing ground for a new plague batch that is at risk of being released to the populace of 40k Victorian London planet. the radical preacher could as some fun to this as well i like where this could be going.
now another idea what about rouge psykers or even astropaths that have certain "organs" removed to create a virulent plague that either effects pskers only or can go as far as release the ability it unto the populace thus creating a great rift in real space or would that be more tzneech than nurgle as nugle would be more fun to play with first then maybe do a chaos round robin. there are definitely many routes that something like this could take i like the can of worms you have opened for me.
now another thing i am wondering is this so my group so far will be just me and my fiances playing around and having fun the charaters will bean adepta sororitas assassin and either a tech priest/heretek type warrior or a psyker warrior and i am know as a sadistic an mean gm as is so it makes me wonder what would be best to screw with a character i make especially if i go with the psyker route (heretek is temping as my fiance likes how eldar tech looks and acts especially harlequins and me being nice would be able to repair her gear for her)
but since you mention khorne i was thinking of a more feudal/feral/forge world route with him on a planet that has a significant resource to the imperial war machine or even to the inquisition themselves. and in there a cult of khorne is being formed as is the beginning of an ork wraaaaaag happening at the same time thus causing mass panic kinda like in the space marine video game.
but any who more input from there would help im off to go plot and scheme.