Idgreatim2-10 Years Gymnastics Leotards for Girls Sparkly Biketards Unitards Athletic Tumbling Outfit

If a child is between sizes, size up or down?

What size fits 3.5 ft and 40 lbs?

What's the right way to put this on? Is the neckline supposed to be higher in front than the back or is the tag in front for some reason?

Is this dress stretchable?