Hi Cricket,
My calves are 13", and I think you saw the photo of me in my boots. I have them buckled to the smallest setting. That works for jeans as well as leggings for me. There's a bit of a gap with leggings/tights, but like Angie mentions, that's the way they are supposed to be.
The boots are easy to get on, but it really depends on the size/configuration of your foot and ankle. Also, depends on what size you get (some people get their shoe size; I got 1/2 a size up because I like to wear thicker socks). With the smaller size, you might initially have problems pulling the boot up (some people have resorted to the "plastic bag in the boot" trick to slide their feet in), but the boot should stretch out after a few wearings and you will have a nice fit.
