The same as the active duty army and reserves do.

Yes. They are separate components, with their own recruiting.

The National Guard and Reserves are branches of the active duty military.

About 550,000 active duty personnel and another 550,000 reserves and National Guard members.

If you are referring to the U.S. Army and Air Force reserves, yes, they are known as the "National Guard." Actually U.S. Army Reserve and Air Force Reserve are federal reserve forces. Air and Army National Guard are state forces that can be federalized by the President.