I think בובת פרווה should be accepted as stuffed animal
I think so too, I don't think anybody says חיה ממולאת.
Yes, the Wikipedia article בובה ממולאת defines: בֻּבָּה מְמֻלֵּאת הִיא בֻּבַּת־פַּרְוָה.
Zot lo khaya memulet, hi amitit!
What's the difference between זו and זאת?
Well, זֹאת was the usual form in Classical Hebrew, זוֹ in Mishnaic Hebrew. In modern Hebrew it is a question of style, which to use. Some think זוֹ should not be used with the definite article.