The World of Imagination is Boundless

The world of reality has its limits;
the world of imagination is boundless.
— Jean-Jacques Rousseau

Today the first question is related to today’s date, October 19th, setting a theme for the remainder. There are two answers required for each question.

One

Jonathan Swift, author and clergyman, died on this date in 1745.  The Wikipedia quote below describes a fictional race from his most famous work but what descriptive word is missing, and what’s the title of the work which has also been removed?

Houyhnhnms are a fictional race of intelligent … described in the last part of … by Jonathan Swift.
— Wikipedia

Two

The Unseen University is located in what fictional city, and as a result of a transformation, the university’s librarian became what?

Three

Mos Eisley is a city in which science fiction franchise, and on which planet is it situated?

Four

In a trilogy published in the early 1950s, a series of short stories explores the decline of a galactic empire, drawing parallels to the fall of the Western Roman Empire. The story centres on Hari Seldon, a mathematician and psychologist, who develops psychohistory, a new science. What is the title of the trilogy and its author?

Five

Arthur Dent, a human, embarks on a journey with Ford Prefect, an alien, after Earth’s destruction. He discovers Earth was a supercomputer designed to uncover the ‘Ultimate Question of Life the Universe and Everything’ and his mind holds the answer. What is the six-word title of this work, and in what medium was it first published?

Good luck! I’ll post the answers later.