Serving a diverse

Sheffield is a Foundation Trust economy serving a diverse population of 580,000 people. NHS Sheffield Clinical Commissioning Group is a membership organisation comprising 79 GP practices and expects to have a commissioning budget (including primary care co-commissioning funds) of circa £900m making it one of the largest CCGs in the country.
I saw the above in one of the nhs vacancies.
Are "serving a diverse.... people" and "comprising... in the country" reduced relative clauses and thus modifying "economy" and "organisation"?

What is the grammatical form and function of "making it...country"?

I am learning to write longer sentences with some variety.