If I've understood your question correctly, it's based on the fact that English has two different verbs to express one verb (you3) in Chinese. This issue exists in Russian and Semitic languages as well. Here's a real quick thought: There is a library in the city. -- Topic / subject / focus is the library. The city has a library. -- Topic / subject focus is the city.

No, that's not a rule. Could you give some examples of what you are talking about?

People and animals have five digits on each one. Places are somewhere. A movie is an abstract thing. Movies are plural. A movie is singular.