Although asymmetrical balance may appear more casual and less planned, it is usually harder to use because the artist must plan the layout very carefully to ensure that it is still balanced.
Value refers to the lightness or darkness of objects.
Large flat areas without much detail can be balanced by small irregularly shaped objects since the eye is led towards the more intricate shape.
Using a balance beam, a larger weight closer to the centre point, can be balanced by a lighter weight further away from the centre. This is the basis for balance by position.
Smaller areas with interesting textures(variegated light and dark, or random fluctuations) can balance larger areas with smoother, untextured looks.
Your eye can be led to a certain point in a picture depending on how the elements are arranged. If the people in the picture are looking in a certain direction, your eye will be led there as well.
The third type of balance is radial balance, where all the elements radiate out from a centre point in a circular fashion. Because all the musical instruments surround his face.
Really good piece of work with the right amount of detail and analysis. Well Done.