Was Elvis considered Regular Army or USAR?

Answer 1

Elvis was US (Conscripted/Drafted). RA was a volunteer (Regular Army) for enlisted men. ALL US Army officers are Reserve Officers on active duty if they're in the Regular Army. The exceptions are West Point graduates who are normally given RA commissions upon graduation, or if there are not enough RA commission openings available the grads are given Reserve Commissions until an opening occurs. US Army Reserve Officers on active duty can apply for and receive RA commissions upon boarding.

If the student historian ever needs a reminder to remember all of those details just remember the movie (film) "Saving Private Ryan", in that film actor Tom Hanks portrays an Army Captain. He relates his background to another GI, and says he was a school teacher before the war...

Which means the captain (Tom Hanks) was a reserve army officer called to active duty for the war.