Short answers, pulled from the story.
Andronicus of Rhodes arranged Aristotle's scattered lecture notes into a specific sequence in the first century BC. He placed a collection of treatises dealing with abstract subjects immediately after works on natural philosophy.
Aristotle himself never used the word Metaphysics to describe his own work because he called the inquiry First Philosophy or the study of being qua being. The title we use today emerged from the accidental placement of manuscripts rather than an authorial declaration.
Book Theta introduces the distinction where potentiality acts as a principle of change within another thing or within itself while actuality represents the completed state of something that previously possessed only potential. This relationship functions like form and matter but adds the dimension of time.
Alexander of Aphrodisias wrote a commentary on the first five books of the text in the third century AD and his name appears on commentaries for the final nine books though modern scholars doubt his authorship of those sections.
W.D. Ross published a general edition in 1924 that argued certain books formed a continuous work while others were inserted by editors. He stated that even combining all accepted books did not constitute a complete single work.