There is no set length for medium hairstyles although they ten to be just shorter than long hairstyles that are usually around shoulder length-ask your local hairdresser for more advice.
layered hair shoulder length or meduim wavy cut
well maybe the side bangs and shoulder length bob.
In my opinion either long hair or shoulder length
There are many online resources such as Style Bistro or Pintrest, that offer pictures and information on shoulder length hairstyles. Alternately, books on this subject can be found at a local library or bookstore. Also, a hairstylist can provide information on what styles suit a person's face shape.
6 inches atleast shoulder length
There are many good hairstyles for round faces. The most popular include a cropped, chin-length hair cut. Another is a longer haircut, often past shoulder length, with side swept bangs.
a pony tail or bun
I have the same type of hair, and I have been just leaving it down, using ponytails, and braids/buns. They all work fine for me. Hope this helps!
I suggest getting a bob cut or cut it shoulder length. Those are very popular hairstyles nowadays.
French braiding usually looks really good with short, thin hair.
The average female torso length, from crotch to shoulder is 22.6". From waist to shoulder, it is 12.5 inches. Source: http://www.pipeline.com/~dada3zen/average.htm