Short answers, pulled from the story.
Christopher Nolan worked on the Inception script for nine to ten years. He first pitched the concept to Warner Bros. in 2001 and spent six months completing the final script after finishing The Dark Knight in 2008. Warner Bros. purchased the spec script on the 11th of February, 2009.
Inception had an official budget of $160 million, split between Warner Bros. and Legendary. It grossed $839 million worldwide, including re-releases, and became the fourth-highest-grossing film of 2010. Warner Bros. spent an additional $100 million marketing the film.
Inception won four Academy Awards at the 83rd ceremony: Best Cinematography, Best Sound Editing, Best Sound Mixing, and Best Visual Effects. It was also nominated for Best Picture, Best Original Screenplay, Best Art Direction, and Best Original Score.
Hans Zimmer composed and arranged the score for Inception, describing it as a very electronic, dense score filled with nostalgia and sadness. The score features guitar work reminiscent of Ennio Morricone, played by Johnny Marr, former guitarist of the Smiths. Edith Piaf's "Non, je ne regrette rien" also appears throughout the film as a plot device to synchronize the dream kicks.
Brad Pitt and Will Smith were the first two choices for the role of Dom Cobb, according to The Hollywood Reporter. Smith turned the role down because he didn't understand it. DiCaprio was ultimately the first actor cast and worked closely with Nolan for months on the screenplay before filming began.
Christopher Nolan confirmed the ambiguity of the spinning top ending was intentional, saying he imposed it from outside the film by cutting before the top's fate is revealed. In 2023, Nolan credited his wife and co-producer Emma Thomas with the correct reading: that Cobb's character doesn't care whether the top falls, because he has chosen to be present with his children. The film's screenplay itself ends with the note that the top is "STILL SPINNING" at fade out.