I work in the National Guard as an officer.
I joined back in 98'  we are part of the reserve components of the United States Armed Forces.
Can you have a civilian job while serving in the National Guard?
You can but you still have to report. National Guard units are under the dual control  of the states and the feds.
I see, and where does the National Guard operate?
We are stationed all over the U.S! he National Guard is a joint activity of the United States Department of Defense (DoD) 
Have any US presidents served on the National Guard?
The National Guard is a joint activity of the United States Department of Defense (DoD) composed of reserve components of the United States Army and the United States Air Force: the Army National Guard and the Air National Guard, respectively.
Local militias were formed from the earliest English colonization of the Americas in 1607. The first colony-wide militia was formed by Massachusetts in 1636 by merging small older local units, and several National Guard units can be traced back to this militia. The various colonial militias became state militias
. National Guard units are under the dual control of the state and the federal government.
The majority of National Guard soldiers and airmen hold a civilian job full-time while serving part-time as a National Guard member. These part-time guardsmen are augmented by a full-time cadre of Active Guard & Reserve (AGR) personnel in both the Army National Guard and Air National Guard, plus Army Reserve Technicians in the Army National Guard and Air Reserve Technicians (ART) in the Air National Guard.