Short answers, pulled from the story.
Dan O'Bannon received sole credit for writing the screenplay despite eight drafts written by others. The Writers Guild of America awarded him this recognition after he and Ronald Shusett developed the initial story.
Principal photography ran from July 5 to the 21st of October 1978 at Pinewood Studios and Shepperton Studios near London. A crew of over two hundred craftspeople constructed three principal sets during this period.
Alien premiered on the 25th of May 1979 at the Seattle International Film Festival before its wide release. It opened in limited American theaters on the 22nd of June 1979 while moviegoers lined up blocks to see it at Grauman's Egyptian Theatre in Hollywood.
The final US gross reached $78.9 million while UK total hit £7,886,000 during first run. Including reissues worldwide gross listed between $104.9 million and $188 million according to industry records.
The film won Academy Award for Best Visual Effects plus three Saturn Awards including Best Science Fiction Film and Best Direction for Ridley Scott. It also won Hugo Award for Best Dramatic Presentation and was selected for preservation in United States National Film Registry in 2002.