I don't know, we already have the Netherhound, and that's primarily based off the idea of angry wolves. I don't think an adorable kitty chasing you would be as intimidating.
I guess you could make it intimidating by making it more powerful than an enderdragon? No, it could be a kitty riding an enderman, and has 100 health.
I don't think this is possible, sadly. Since cats are jerks and like to tip stuff over, why don't they just empty the contents of nearby chests
xD yeah that would be a great idea. And the spawn rates should be higher, so if they spawn in your makeshift house, your screwed lol.
Endercats Once they get close to you then you'll risk them nabbing something from your inventory after which you'd better fight them quick before they're gone. Favorite items to nab: wool (because its fun) and shiney items such as iron and gold ingots
Ah yes, that sounds real interesting! Also has a 1% chance of teleporting your items into a dropper and chest nearby.