^ This is reference to the spanish movie "Dagon"
It was the most direct inspiration for the Cult of Dagon faction in the first place.
I recommend that movie, even to people who don't like horror much.
But what you are describing is something else. It's be cool to have such reports too, but at this point I don't have any. We'll see.
Are these dossiers for points basically and to give my poor poor overworked researchers some more to do? 
Yes!
To give you points, fluff and science problems.
Will the dossiers provide some benefit for ground troops in some capacity either directly or indirectly?
Unlikely, though it's not completely ruled out. I just don't have a concept yet.
I love the idea of findable documents which based on XYZ (level, faction, WTFE) and could act as a great element. I mean being able to raid a cult outpost and finding info that blows open the network of ANOTHER cult by pure chance sans interrogations is something I'd giggle about. I mean the cults might keep tabs on each other right? 
That's the general idea, yes.
Dossiers of persons thought interesting, Weapon sourcing, equipment plans, mission data types, etc etc etc. That sound really cool... I'd also love to see exposed 1 off missions that fall in the realm of "OHH GOD THEY'RE COMING OUT OF THE GODDAMN WALLS!!!"...but you were saying it takes a lot of work to do that.
Well, it doesn't mean it won't happen... Just not very soon. I want to tackle major things first (currently the Syndicate arc).
I can see why you have been wanting to somehow get rescueable civilians too. That's a really great tool for storytelling or for exotic rescue missions.
Yes, I have a few ideas. Mostly rescue missions.
I have noticed that stunning the Madmen doesn't get me anyone to interrogate. I've tried several times always making sure to have prison and pen room and no luck... feature or bug?
Are you saying they aren't recovered at all? Or can't be researched?
Because if you mean research, then yeah, they can't be interrogated. They don't have anything interesting to say.
Dossiers could also be a place couldn't they? a place that X-com is interested in. Weather it relates to anything else is whatever...but I bet it could get you some ideas for stuff.
Perhaps, but for now I want to focus on people. Still, if you have ideas, fire away - I can always save it for later.
Are you going to also include plot artifact items that spawn on certain maps? To be used as a plot starter, filler, or even a tech boost?
Maybe later. For now, too much work, too little gain. I need to keep some discipline here, or we won't get far.
I'd personally love to see more time sensitive missions... but I'm not really all that far in this latest version. so... you know.
Oh, I have great plans.
I'll work up some flavor text and a picture to be associated with a place for teh lulz and see if you like it.
Sure, give it a try if you want.
I will add two.
I'll skip Jackal, since I know about him, my mum knows about him, people living on Kamchatka probably know him... And so X-Com probably knows about him too.
But I'll take Ms. Foster, thanks.
