Short answers, pulled from the story.
Frostating was located at Tinghaugen near the medieval church at Logtun in what is now Frosta Municipality. This hill served as the seat for one of four ancient popular assemblies in medieval Norway.
King Magnus the Lawmender promulgated a new national law on the 2nd of May 1274 with consent from all existing assemblies. This unified code replaced the older Frostathing Law and significantly reduced the assembly's legislative power.
Authority extended over eight districts within Trøndelag including Nordmøre and Fosen alongside Namdalen. Later expansions brought Hålogaland under its jurisdiction before centralization efforts began.
An original seal dated the 1st of June 1453 depicts King Magnus seated on his throne handing the new Frostating law to a lawman while delegates stand three deep on his left side. A crown adorns the king's head and he holds a scepter in one hand.
Frederik III introduced absolute monarchy in 1660 ending centuries of representative governance across Norway. The King Act of 1665 codified this shift functioning as Norway's constitution until 1814.