In regards to her tail and head, I think that's merely artist's preference. I can see how at first glance the tail's position, shape, and size can make her figure out to be very "jabba-ish," but misleading anatomical imagery exists in real-life photography, as well.
When it comes to a drawn picture (like Chloe here), a smaller head relative to the body can give a slight sense of bulkiness or help exaggerate other key elements of the body. In this case, her breasts, thighs and overall femininity are meant to be one of several focal points. It adds a sensuality to the image. The overly-sized tail - I can only guess - is meant to exaggerate "fluffy-ness."
But that might just be looking to deep into things. I'm guessing Jackson just wanted to make a sexy picture.