OOFOSUnisex OOriginal Sport - Post Exercise Active Sport Recovery Thong Sandal

Are these Men's o Women's size?

SO confusing! Some of the reviews say the sizes run small, some say they run large. I wear a size 8 1/2 shoe...and don't know what size to order.

How high is the heel?

Does it take some time to get used to wearing? Wearing one day and one leg is starting to ache.