Each of the formal elements serves its own purpose and place in the piece pictured. To know how to identify their specific usage, one should first consider what each of these elements is.
Line: A line is an obvious path that one can follow from point to point. Lines vary in length, width, and direction, and are often used as a means to identify where the boundaries of one object begin and the boundaries of another end.
Shape and form: These two elements are used to define the existence of an object in a two-dimensional or three-dimensional space (respectively). Shape is usually defined by the line and has height and width. Form has height, width, and depth.
Color: Color comes from the light that's reflected off objects and is created from hue, intensity, and value.
Value: Value refers to the brightness of a color, which is used to suggest the existence of light (or lack thereof).
Texture: Texture is how we perceive an object's quality through touch. In the case of the painting above, since you can't touch it, the type of texture used is two-dimensional and exists to suggest to us the qualities the painting would have if we were to touch it.
Space: There are both positive and negative versions of space. Positive space is used to define the area in which an artist's objects exist in the painting while negative space describes the unused area around said objects.
So you can see how each of these elements works together to create the painting. Researching the principles of art will allow you to see how those principles fit in with the elements and ultimately help you answer the questions posed.