Short answers, pulled from the story.
The final budget reached $15.175 million, making it the most expensive film ever produced at that time. The budget had started at $7 million and climbed to $10 million by February 1958 before reaching its final figure when principal photography began.
The chariot race was directed by second unit directors Andrew Marton and Yakima Canutt. William Wyler directed the pageantry sequence before the race, the crowd reaction shots, and the victory scenes afterward.
Ben-Hur won eleven Academy Awards from twelve nominations at the 32nd Academy Awards. The only category it lost was Best Adapted Screenplay, which went to Room at the Top. Its record of eleven wins has since been matched only by Titanic (1998) and The Lord of the Rings: The Return of the King (2004).
Vidal arrived in Rome in early March 1958 and worked primarily on the first half of the script up to the chariot race. He rewrote nearly all the dialogue from previous drafts, split the reunion between Ben-Hur and Messala into two separate scenes, and scripted ten versions of the scene where Ben-Hur confronts Messala about his family. Christopher Fry later rewrote as much as a third of the dialogue Vidal had added.
No horses were injured during the chariot race, which was a deliberate departure from the 1925 silent version during which at least one hundred horses reportedly died. Stunt man Joe Canutt, son of second unit director Yakima Canutt, was thrown into the air during filming and suffered a minor chin injury. That accidental shot was incorporated into the final film.
At the time of its release, the Ben-Hur score was the longest ever composed for a motion picture, running to more than three hours with about two-and-a-half hours used in the film. It held that record until 2021, when the score of Zack Snyder's Justice League surpassed it. It was also the first film score released both in its complete form and as a separate condensed album.