The only time to be concerned with either of these things is if there is a marked difference between the two sides, pain, associated poor growth, or an unusually severe degree of curvature which your pediatrician will note. When buying shoes there are certain guidelines to keep in mind. Shoes should be flexible, breathable, porous, have good tread and traction with flat soles. They should be shaped like the foot - no pointy toes. Growing room should be allowed by having 1-1 cm between the end of the toe and end of the shoe.
High tops are only useful to prevent the child from removing the shoes.
They are not necessary as ankle supports. Shoes provide protection when outside - inside bare feet are just as good for the development of feet and walking. The best reason to have children wear shoes in the house is simply so they are accustomed to it and won't fight putting them on at other times. Since children grow rapidly don't feel you must buy expensive shoes. White, high top leather walkers are not good shoes anyway.