KBZoneWomen's Flats Slip on Ballet Flats Wide Toe Box Comfortable Walking Shoes

The size chart is a bit confusing...My heel to toe is about 9.5" which says I should get a 6, UK 37, my birks are 41UK. I wear 9/9.5. Size to get?

Can someone with a size 8 or tell me the interior dimension or the insole at its widest point?

Are these shoes machine washable?

What are the width measurements for each size?