Short answers, pulled from the story.
Adam of Bremen wrote Descriptio insularum Aquilonis describing an island called Winland where grapevines grew by themselves. The Latin text states that the vines produce the best wine and relies on information from King Svend Estridson of Denmark.
Helge Ingstad and Anne Stine Ingstad discovered remains of a small Norse encampment in northern Newfoundland in 1960. Radiocarbon dating confirms the site's occupation was confined to a short period around 1000 CE with wood cut in 1021 using metal blades.
Leif Eriksson organized an expedition retracing Bjarni Herjólfsson's route past flat stones and forests. He returned to Greenland with a shipload of timber and a boatload of grapes after establishing a base where he found grapes and timber.
Erik Wahlgren examined the question in his book The Vikings and America published in 1986 and pointed out clearly that L'Anse aux Meadows cannot be the location of Vínland. The sagas describe both salmon in rivers and vínber growing freely which does not match the site.
Archaeologists found butternuts at L'Anse aux Meadows indicating voyages into the Gulf of Saint Lawrence because these nuts grow only as far north as northeastern New Brunswick. Birgitta Wallace identified butternut remains in the Norse stratum as the smoking gun linking the environment.