Short answers, pulled from the story.
The name Gerðr appears in the Poetic Edda, a collection compiled during the 13th century from older oral traditions. Snorri Sturluson wrote about her in two books of the Prose Edda and in Heimskringla, another work from the same era.
Freyr saw a beautiful girl walking from the hall of her father Gymir to a storehouse while sitting on the high seat Hlidskjalf. His servant Skírnir rode over nations and dew-covered mountains until he reached Jötunheimr to negotiate with her.
Chapter 12 of Ynglinga saga presents a prose account where Freyr was a much loved king in what is now Sweden and his wife was named Gerðr. Their son was Fjölnir who went on to become king after Freyr died.
Scholar John Lindow notes that Gerðr's name has been etymologically associated with earth and enclosures. The wedding of Gerðr and Freyr is commonly seen as the divine coupling of sky and earth or fertility god and representative of soil.
Almost 2,500 small pieces of gold foil featuring engravings dating from the Migration Period into the early Viking Age are known as gullgubber. These items were discovered largely at sites of buildings rather than graves and sometimes show a man and woman with a leafy bough between them facing or embracing one another.