Short answers, pulled from the story.
Disney formally announced the project to The New York Times in June 1934. This announcement came after he decided to produce the first full-length animated feature film in American history. The decision was made in the spring of 1934 and cost over $1.4 million to complete.
Adriana Caselotti was the voice of Snow White in the 1937 film. She was cast in September 1935 after auditioning about 150 other actresses. Caselotti recorded her first tracks on the 20th of January 1936 and spent forty-four days in recording sessions over two years.
The character of Dopey was introduced in November 1934 but was originally very talkative. No suitable voice actor could be found for the role, leading to the decision to make him mute. He was the only dwarf who communicated through sounds and pantomime.
Animators added color to the characters faces by using a red dye with a small piece of cotton wrapped around a tipple pencil on each individual cel. This method was so time-consuming that it was never used again on the same scale. The process gave the characters a lifelike quality that set the film apart from previous animations.
Roy Atwell voiced Doc, Billy Gilbert voiced Grumpy and Sleepy, and Pinto Colvig voiced both Grumpy and Sleepy. Eddie Collins voiced Dopey, the only dwarf who communicated through sounds and pantomime. The dwarfs were voiced by a group of actors who brought distinct personalities to life.