Is there a way other than manually adding an item to every single creature and NPC that would make it drop with every kill?

I've scripted a new line of magic, and very happy with how it works, but it's all powered by a custom item, "Blood". I have the custom item made with model and texture, but is there any way to make it a universally dropped item? (Excepting skeletons and ghosts, of course...neither has blood)

Also, part of the magic system uses sacrifices...hearts, that is. I have 3 classes of hearts...beast hearts (rats, cliff racers, katougis, etc), daedra hearts (already in the game), and human hearts. Now, with the beast hearts my question is the same as above, how can I add those as a random chance...say 25% drop rate, to critters?

With the human hearts, these would only exist on NPCs, so I think I would have to manually add those to their inventories, but I'm not sure how to do that with them existing as a 10% drop rate. Is there anyway, either with a simple 'humanoid kill counter + If ( Random >=90 ) + AddItem' function in a small global script, or with a randomized drop function, to do this?

Thanks ahead of time if anyone can help me out with this. Also, if these ideas aren't doable, any suggested workarounds are definitely appreciated.