BezionerBallet Dance Shoes Split Sole Flat Gymnastics Dancing Slippers

My daughter is a kids size 9 your description says to go a size up is that right or should I get a size 9

will size UK 4 be suitable for a 9 year old girl?

I'm a uk size 9. they only do 9.5. would they fit? (i only need them for a show i'm doing and i'll most likely sell them afterwards)

How do you wash them?