The texture pack Craftee pack advertized random mobs, and they worked for me. I opened up the texture pack, and they have placed a folder in there titled 'mcpatcher', with everything you'll need as a template. The mob number system has not changed.
To anyone experiencing this wool problem, it is because of Optifine for Minecraft 1.5. If you switch to their latest, 1.5.1, you should have no troubles.
That's what I'm thinking, but I'm not sure how. I have it under the 'items' folder and not 'blocks', and as far as I know, you're supposed to simply name it compass. I tried adding the txt compass file too, which made my compass work fine, but it's not resolving the issue of the switching textures.
I personally use Optifine, and it's not helping me nor my server buddies at all. Also, Optifine only fixes custom textures to my knowledge, such as lava and water.