-1- What was the U.S. army's official rifle and side arm at this period?
According to Chris Taylor (Fallout lead designer), the military was mostly using laser weaponry at that point. According to a Museum of Technology exhibit, the http://fallout.wikia.com/wiki/M199_Assault_Rifle was the official rifle, but it's contradicted by the Citadel entry for the R91 Assault Rifle, which states that the M series was discontinued in the early 21st century.
-2- What was the specific time period during which the reclamation occured, and all important former events
See:
http://fallout.wikia.com/wiki/Anchorage_Reclamation