REEFStargazer Women's Beach Flip Flop, Super Lightweight and Soft Footbed, Thin Glitter Strap

I wear a size 7.5. If I order a size 8 (since I read in a previous question that they run small) will it be an 8/9, and in that instance be too big?

Is there a cloth strap between the toes?

Do they run small?

Is this waterproof?