Short answers, pulled from the story.
Winnie-the-Pooh was created by English author A. A. Milne, with illustrations by E. H. Shepard. The character first appeared by name on the 24th of December 1925 in a Christmas story commissioned by the London newspaper Evening News.
The name Winnie came from a real Canadian black bear at London Zoo. Lieutenant Harry Colebourn of the Fort Garry Horse cavalry regiment bought the bear cub from a hunter for C$20 in White River, Ontario, during the First World War, and named her after his hometown of Winnipeg, Manitoba. After the war she was officially donated to London Zoo, where Christopher Robin Milne regularly visited her.
Ashdown Forest is an area of open heathland in East Sussex, England, situated 30 miles south-east of London. A. A. Milne bought Cotchford Farm, near Hartfield, a mile north of the forest in 1925, and used its landscapes as the direct inspiration for the Hundred Acre Wood. Christopher Robin Milne wrote in his autobiography that "Pooh's forest and Ashdown Forest are identical."
Shepard based his illustrations of Pooh not on Christopher Robin's bear but on his own son Graham's teddy bear, named Growler. Both Shepard and Milne felt Christopher Robin's bear was too gruff-looking, so they agreed to use Growler as the model instead.
E. H. Shepard's original 1926 illustrated map of the Hundred Acre Wood sold for £430,000 at Sotheby's in London in 2018, setting a world record for book illustrations.
A. A. Milne's US copyright on Winnie-the-Pooh expired on the 1st of January 2022-95 years after first publication of the first story. UK copyright is set to expire on the 1st of January 2027, the first day of the first calendar year at least 70 years after Milne's death.