Short answers, pulled from the story.
Avengers: Age of Ultron had a gross production budget of $444 million, with a net budget of $365 million after $50.7 million in UK tax offsets. This makes it one of the most expensive films ever made.
Joss Whedon wrote and directed the film. He changed Ultron's origin from the comics, where Hank Pym creates the villain, because the Ant-Man character was already tied to Edgar Wright's in-development project and because he felt it made more narrative sense for the Avengers themselves to be responsible for creating their own adversary.
Avengers: Age of Ultron grossed $1.403 billion worldwide, earning $459 million in the United States and Canada and $943.8 million internationally. On the 15th of May 2015, it became the twenty-first film in cinema history to cross the one-billion-dollar mark.
Principal photography took place primarily at Shepperton Studios in Surrey, England, beginning in mid-March 2014 and completing on the 6th of August 2014. Additional locations included Johannesburg in South Africa, Fort Bard and the Aosta Valley in Italy, multiple sites in Seoul and Gyeonggi in South Korea, Chittagong in Bangladesh, and the state of New York.
Joss Whedon described Spader as his first and only choice for the role, citing his hypnotic voice that could be eerily calm and compelling while also being human and humorous. Marvel's Kevin Feige clarified that Spader's full face and body were motion-captured to create the performance, rather than recording only a voice.
The first trailer, released officially on the 22nd of October 2014, after leaking online, received 34.3 million global views within 24 hours. Of those, 26.2 million came from Marvel's YouTube channel, breaking the previous record set by the Iron Man 3 trailer's 23.14 million views.