According to the "Daggerfall" manual, "There are more than fifty varieties of adversaries you may face in the course of your adventures." By my last count, I've got 57 listed here (kinda like Heinz' "57 varieties"), so if I'm missing anything, it's not for lack of trying.  I have included combat info from Bethesda's hint book regarding armor class and health.  As far as I can tell, it's still accurate, except for the Health statistic which tends to be toward the high end.  My best guess would be that critter health works like level health points -- somewhere between 50% and 100% of the maximum.

A few things to keep in mind about critters and their treasures:

First, there is absolutely no relation between the type/class of critter you kill and the goodies they have when you search the body. Lamia and Dreugh (who have no legs) can be found with greaves. Thieves can be found with plate armor. Ghosts can be found with coins (I’d really like to know where they keep it). Archers almost never have arrows or bows. In other words, don’t look for logic regarding what the critter can do and what it carries.

Second, what you find on the body has a great deal to do with your Luck attribute and your level. The higher your Luck and your level, the more gold you'll find and the better your chances of finding stuff made of better materials.

Third, you’ve got to kill the critter to get its goodies. You can try to talk it out of fighting (if it has a language), but you can’t talk it out of its treasure.  This would have been a great place for Bethesda to have effectively used the Pickpocket skill. Pickpocketing the critter could have actually taken items out of its inventory rather than a random 1 to 5 gold pieces.