HanesGirls' and Toddler Assorted Briefs

Would they fit over a diaper?

Is 2/3 the same at 2T or 3 T?

Tienen la tabla del tamaño??

Will these shrink after washing and drying in the dryer? The 2-3T is like a size 6 from a different brand but i worry that it will shrink too much.