dialectical materialism

In the brief introduction to course A you refer to dialectical materialism
Do I understand this as follows:
motion is the mode of existence of matter and matter cannot exist without motion. That opposites are to be found everywhere in nature and by the continual conflict of opposites the life of nature is determined.
Do I take this to mean that dialectical materialism in the perspective of TCM is the insistence on the absence of absolute boundaries in nature and on the transformation of moving matter from one state to another.

Your understanding is right!
So, you can understand more the Yin-Yang theory. When it means the left is Yang while the right is Yin, it's all relative. When you stand in one place, so your left side is Yang, but moving a couple of steps to the right, the original place would become left, so it changes from Yin to Yang.
The same to the organs.
The text tells that the infinite dividing among the organs would lead to the new understanding of the Zang organs, so the liver, spleen and kidney are relative more Yin while the heart and lung are relatively more Yang, while the further comparison between the heart and lung would tell that the heart is more Yang than the lung.
Only when there is man, so there is woman, otherwise you don't have to divide the human beings as man and woman.
The dialectics would tell alot about the relativity of this universe and all the substance and phenomina, so it is related more to the Yin-Yang theory.
While when you study the Five-element theory, you may find the relationship between or among different substance or materials or the other phenomina.
That's the philosophic basis of traditional Chinese medicine.
However, it is not denied that each organ individual has something special.
So the general rules and the individual rule can make the things more complicated, and this is also quite obvious in traditional Chinese medicine so it takes you alot of thinking to grasp the essence of traditional Chinese medicine.