When Felix asks Oscar how he found the apartment, Oscar tells him, 'Like everybody in New York got their apartment, by looking in the obituary columns, see who died in a good neighborhood, then rushing around to try and grab it.' This is actually how many New Yorkers have done it (and continue to do so, as New York's rent laws are unique; apartments come in several categories; rent controlled, stablised, and market rate - price-wise this is from best to worst, and New Yorkers have - since the 1930's - tried to find these coveted rent controlled apartments. People have gone so far as to demand they be allowed to stay in such an apartment and have it be written into divorce decrees.)
The exorcism would cost $500 which is equal to $2930.51 in 2021.
The (obvious answer as to this epsode's title, is it's based on the film, The Exorcist (1973)) which was the film of 1973 (aside from the other film about a certain Italian-American group). This film's popularity lead to many spoofs, knock-offs, etc., In TV, in film, and books, all having to do with other-worldliness.
Postman Irving Cohan lived (and died) in the apartment before Oscar and Blanche.