What four major contributions did the Roman Republic make?

1. What four major contributions did the Roman Republic make that define Western Civilization? Fully discuss and explain these contributions.
2.Discuss how the role of emperor, senate, and army changed under Augustus as Imperialism evolved. Explain the duties of the emperor under the Imperial system.

The answer to each question should contain a minimum 200-word response.
Please list all reference.
Make certain that all of your sources (including your textbook) are referenced at the end of the response and that the information within the response is cited to show the difference between your ideas and your sources.