The following article contains an answer for the question: What is the first name of the person Koster let use the studio when it was empty? , can you please find it? 

In 1987, Trent Reznor played keyboard in a Cleveland, Ohio band called the Exotic Birds, then managed by John Malm Jr. Reznor and Malm became friends, and when Reznor left the Exotic Birds to work on music of his own, Malm informally became his manager. At the time, Reznor was employed as an assistant engineer and janitor at Right Track Studios,  in Cleveland; he asked studio owner Bart Koster for permission to record some demos of his own material for free during unused studio time. Koster agreed and allowed Reznor to use it whenever it was empty, commenting that it cost him "just a little wear on [his] tape heads". While completing the early recordings, Reznor was unable to find a band that could articulate the material as he desired. Instead, inspired by Prince, Reznor played all the instruments, except drums, himself. This role remains Reznor's on most of the band's studio recordings, though he has occasionally involved other musicians and assistants. Nine Inch Nails' debut was at the Phantasy Theater in Lakewood, Ohio on October 21, 1988 as part of the Pretty Hate Machine Tour Series. In 1988, after playing its first shows supporting Skinny Puppy, Reznor's ambition for Nine Inch Nails was to release one 12-inch single on a small European label. Several labels responded favorably to the demo material and Reznor signed with TVT Records. Nine selections from the Right Track demos recorded live in November 1988, collectively known as Purest Feeling, were later released in revised form on the band's first full-length studio release, Pretty Hate Machine (1989). The overall sound on Purest Feeling is lighter than that of Pretty Hate Machine; several songs contain more live drumming and guitar work throughout, as well as a heavier use of samples from films.Reznor coined the name "Nine Inch Nails" because it "abbreviated easily", rather than for "any literal meaning". Other rumored explanations have circulated, alleging that Reznor chose to reference Jesus' crucifixion with nine-inch spikes, or Freddy Krueger's...

Trent