Short answers, pulled from the story.
Peter Pan was created by Scottish novelist and playwright J. M. Barrie. The character first appeared in Barrie's 1902 adult novel The Little White Bird, where Peter is depicted as a seven-day-old baby living in Kensington Gardens. Barrie then placed Peter at the centre of his stage play, which premiered on the 27th of December 1904 at the Duke of York's Theatre in London.
Barrie drew on two main sources. His older brother David died in an ice-skating accident the day before his 14th birthday, and Barrie's family came to think of David as forever a boy. Barrie also drew from his friendship with the Llewelyn Davies boys, writing in his Dedication to the play that he made Peter "by rubbing the five of you violently together, as savages with two sticks produced a flame."
Barrie gave the copyright to the Peter Pan works to Great Ormond Street Children's Hospital in 1929. Although the works are now in the public domain, the hospital retains the right to collect royalties from adaptations in the United Kingdom under a special amendment to the Copyright, Designs and Patents Act 1988.
The original Peter Pan statue, commissioned by Barrie and sculpted by George Frampton, was erected overnight in Kensington Gardens on the 30th of April 1912 as a surprise to the children of London. Seven statues in total have been cast from the original mould; the other six are located in Brussels, Bowring Park in St. John's Newfoundland, Johnson Park in Camden New Jersey, Queens Gardens in Perth Western Australia, Sefton Park in Liverpool, and Glenn Gould Park in Toronto.
The Peter Pan syndrome describes individuals, typically male, with underdeveloped maturity who have never fully grown up. American psychologist Dr. Dan Kiley popularised the concept in his 1983 book The Peter Pan Syndrome: Men Who Have Never Grown Up. He followed it with The Wendy Dilemma in 1984, which addressed women in relationships with such individuals.
In the original UK productions, Peter Pan's costume was a reddish tunic and dark green tights. Nina Boucicault wore this costume in 1904, and it is now exhibited at Barrie's Birthplace. A green costume became more common from the 1920s onward, and the shift accelerated after the release of Disney's animated film.