Interesting. I get this odd feeling that the Mancubus is a bit too clean. The original is more crudely put together, with more traces of exposed muscle, and having that ugly bloody drool in their mouths. I also feel they are a bit slender, the original mancs have super broad shoulders. But this looks more like a demon that ate too much of whatever demons eat when not invading mankind (broccoli?), instead of being naturally huge.
Other than that, the design is very interesting, specially the head, and the animation is put together very well, I like how it seems like they laugh when shooting, and the machine parts look very good, too!
The Caco is obviously incomplete so it's harder to critique. I think it looks proper so far, although I think the Caco's "demon smiley face :D" is downplayed a bit. The original sprite has the upper edges nearing its eye. And you are missing a pair of horns. And the bottom is like stringy.
Everything else looks quite faithful so far.
I hope I don't sound like downplaying your work, it's very good and definitely better than most models around, just trying to give feedback. This looks quite promising, so keep it up :D
I can't offer to work hand-to-hand in DECORATE and ACS as my hands are full at the moment, but if you got any specific question drop me a PM and I'll help, if you don't have someone else already.
I'm really interested to see how this project will evolve! 
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