Short answers, pulled from the story.
Conan the Barbarian was directed by John Milius, who also co-wrote the screenplay. Oliver Stone was the original screenwriter, but Milius rewrote the script substantially after being appointed director in early 1979.
Conan the Barbarian grossed between $68.9 million and $79.1 million worldwide in ticket sales against a production budget of $20 million. By 2007, home video sales had pushed the film's total gross earnings to more than $300 million.
Schwarzenegger undertook an 18-month training regimen before filming began, which included running, weightlifting, rope climbing, horseback riding, and swimming. He reduced his weight from 240 to 210 pounds and trained in sword-fighting styles under karate master Kiyoshi Yamazaki from August 1980.
Principal photography took place in Spain, primarily in the regions around Madrid and the province of Almeria, over approximately five months beginning on the 7th of January 1981. Filming started at Shepperton Studios in England in October 1980 for an opening sequence, and Spain was chosen after Yugoslavia was dropped due to political instability.
Basil Poledouris composed the score. He was hired before principal photography began and recorded the music in Rome over three weeks from late November 1981, using a 90-instrument orchestra and a 24-member choir from the Accademia Nazionale di Santa Cecilia and the RAI National Symphony Orchestra.
Sandahl Bergman won Best Actress at the 10th Saturn Awards and the Golden Globe Award for New Star of the Year at the 40th Golden Globe Awards for her role as Valeria. The film was also nominated for Best Fantasy Film, Best Costumes, and Best Make-up at the Saturn Awards.