I didn't get a chance earlier to talk to your other points.
I like the armor changes. I wonder if it would be better to raise the heavy armor to a 2 value, but keep them as a 2 body slot item. The light armor could be separated to a shield w/ armor value 1 and 1 paw and the armor as 1 armor slot and 1 body slot. This would allow a light armored mouse with two light weapons, or a bow and quiver. Or a super tanky mouse, heavy armor and shield, medium or light weapon.
I would like to know about the supplement part as well, I want to add more to the beasts, like beetles, ants, bees, wasps, moles, squirrels, chipmunks, weasels etc.