Short answers, pulled from the story.
The Shire stretched 40 leagues from east to west and 50 leagues from north to south. A river named Brandywine bordered the main part of the territory on the east side while Hills rose up to meet the northern boundary near Evendim. Marshlands defined the southern edge and the Far Downs marked the western limit.
Hobbits first settled the region in the year 1601 of the Third Age. Brothers Marcho and Blanco led the migration across the Misty Mountains after living in the wilds of Eriador.
Frodo returned with Samwise Gamgee, Merry Brandybuck, and Pippin Took to liberate the region during a final battle at Bywater. Trees were restored using soil from Galadriel's garden in Lothlórien which went to Samwise Gamgee before the year following the liberation became known as the most productive and prosperous in history.
Tolkien created the Shire calendar based on Bede's medieval system where twelve months each contained thirty days. Five non-month days completed the 365-day year while two Yuledays marked the turn of the year starting on the second day of Yule.
J.R.R. Tolkien modeled the landscape upon rural Worcestershire and Warwickshire where he lived and grew up. The latitude of Hobbiton matched that of Oxford around 52 degrees north and the name Farthinghoe in Northamptonshire triggered the idea of dividing the land into four parts.
Peter Jackson filmed scenes near Matamata in New Zealand for both The Hobbit and The Lord of the Rings. Games Workshop produced a supplement in 2004 for The Lord of the Rings Strategy Battle Game which included rules for miniatures depicting the Shire after the War of the Ring concluded.