If I both have access to the power and authority in a nation or nations to alter the genetic makeup of its people and have the desire to alter said genetics to create a more powerful and better quality of life for said people in said nation, then which of following questions is possible for me to do according to today's science?

A. Is possible for me to alter traits of adults alongside unborn children?

B. Is it both possible and is it more "effective/beneficial" for a society to make everyone "exceptional" at conceivably anything with stuff like art, science, engineering, military etc. or is it more "effective/beneficial" create a genetic cast of people that are specialist for fields art, science, and so on all the while keeping a high medium standard of health and IQ?

C. What are the possible side effects, be it genetically and/or socially If I do either or both of questions A & B? Examples like easy to spread diseases.