Martin: It's about a sicko loner kid named Martin who goes around drugging and killing people, and calling into a radio show and telling them he's a vampire. But none of the vampire rules apply to him (sunlight, mirrors, etc.) and he even pulls fake vampire teeth out of his mouth and says that none of the vampire stuff matters, it's like a deconstruction. The movie came out in 1977 and is set in this utterly dead decaying lonely Rust Belt looking town and the purpose of it is to cynically ask whether or not it even matters if this kid is a vampire in a world this crappy. Romero said he thinks Martin is just a sick kid.
Your anecdote about BI and Showgirls reminds me of the movie Super Dark Times where some kid brags about freeze framing his VHS tape of True Lies. (It's set in the mid 90s) The Bruce Willis movie is some dumb lurid cop thriller from 1994.
Shadow Of A Doubt, gotta love Joseph Cotten rising from his bed like a vampire and snarling about "the moron millions." Of what you missed, the most essential ones are The Lady Vanishes, Rebecca, Rope, Dial M For Murder and Frenzy.