"did anyone else think it was cool what michael keaton did with the razor blade?" Oh yes
"also who was his friend??????" I'm guessing his partner, he helped remove all the fixtures in the apartment
"why were there cockroaches???" He just liked to fu ck with people
"why was there a monkey in the picture???" He came from a rich family, eccentric rich people always have exotic animals for their children to play with, or maybe they were at the zoo
"why was he smoking in his car in a dark garage???" As previously stated, he liked to fu ck with people