I mainly separated heavy armor like I did because it created a similar realism issue for my group where they couldn't wear a quiver just because they had a helmet and breastplate on. For a larger audience that doesn't nitpick near as much, the changes you're suggesting would probably be better.
As for the beasts thing, the rules actually lay out how to make beasts and additional races pretty well given the examples. An expanded bestiary would be nice though. Weirdly moles would work well as a ghoul analogue for the system.


So what I've decided is that the shield and Helm roll their usage die immediately and prevent damage and take a usage only on a 4+. So if you are wearing all three and you take 5 points of damage you roll a die for your shield and a die for your helm. Lets say you get a 5 for the shield and a 2 for the helm. Your shield takes one point of usage and you take 3 damaged (5 - 1 armour - 1 shield). The armor only takes usage damage at the end of combat, and as before you can sacrifice your shield at any time after finding out the result of an attack to cancel it entirely.