Dc Comics Supergirl Child Costume

Are the boot tops supposed to go OVER a pair of the child's own boots?

I'm so confused about the sizing. my daughter is four, 36" tall, with a 20" waist. she generally wears a 3t. what does that translate to here?

daughter will be 13 months when she wears this currently at 11 months she is in size 18-24 months weighs 26lbs Would the 1-2 year old size fit her

My daughter is 7 years old and 48" tall. Should I do a medium or a large?