In these readings, Ching explains how a structural units has its own use in terms of how big it is, and how much space it creates.. An example is that a two way slab and four columns would usually represent a horizontal layer of space. Ching also introduces spans and patterns, and explains that each has a purpose in design. For example, if there is a large horizontal slab, it usually determines the space of each vertical support, in which they should be related. Patterns in a design usually leads to grids, and grids have a huge meaning in design. Grid lines would usually be beams and load bearing walls, while intersecting lines would indicate a column. In terms of lateral stability Ching talks about how some structural units depends on each other, due to how much weight it may support. The best example would be two columns and one beam going across them. Another would be a horizontal slab with four columns supporting it, even adding a fifth on in the center if necessary. These structural information is important, because it literally balances anything being built.
Your summary is good but can use some clarification. For example, define more clearly what lateral stability refers to and how Ching gives us guidance to solve this problem in building structures.