I would highly suggest not wearing character shoes. Just dress normally, yoga pants and leggings are fine with an appropriate top. What you wear shouldn't hurt your chances of getting past the first cut, but at the same time I'm sure the judges can tell if you're trying to hard. They only care about the face and if you can fit in the costume.
And about the tatoo on your ankle. if stockings can cover it or shoes can cover it it should be fine.