About the Half-Demon-Fox, they have that in the Oriental Adventures expansion, its called a Henge Youkai, they're kind of hax but have a high level adjustment if I recall.
As far as the firearms issues go, find the Iron Kingdoms Hand Book, that would help out a great deal. As far as firearms being made in a world without them, I'd say why not? People get ideas and the world keeps turning the real problem with being DM is that you need to actually portray changes in the world and characters.
But reading about the Paladin issues I now want to make a Paladin who worships a bardic god and likes to disco.
And finally on those sex issues: download the book of erotic fantasy, yes its real, yes I have it, yes I'm going to offer its classes, spell selection and so forth to my PCs because you never know when the Disrobe spell will come in handy when I throw opponents with magical armor at them.
Regular D&D:
Me: You are being attacked by-
My Older Brother: I use Gate of Babylon.
(Yes my older brother found out how to copy Gilgamesh's Gate of Babylon from Fate/ Stay Night. And I worry.)