Short answers, pulled from the story.
Gunnar Gjermundbo discovered the Gjermundbu helmet on the 29th of March 1943 while digging an embankment at his farm near Haugsbygd. The University of Oslo collection received notification from local historian Jon Guldal on that same day.
The restored Gjermundbu helmet sits on display at the Museum of Cultural History in Oslo. It remains one of only two fully reconstructable Viking helmets known to exist alongside the Tjele helmet fragment.
Gjermundbu I contained fragments of chain mail alongside a ceremonial sword of Jan Petersen's type S, two spears, and two axes. Four shield bosses, two spurs, and five or six bits also completed the inventory of items found beneath the elongated mound.
Helge Braathen dates the Gjermundbu grave to the latter half of the 10th century. Frans-Arne H. Stylegar suggests the man's grave connects to Viking ties with Kievan Rus.
No other finds in Scandinavia or Western Europe contain both a helmet and chain mail from this period. The site includes one of only five known Viking helmets ever identified by archaeologists.