Haruko refers to Naota as "Taro-kun" several times during Episode 1. Taro is perhaps the most generic name in Japan for a boy, and it used as a placeholder for unidentified Japanese males (like John Doe).
Despite the title's spelling, the title is intended to be pronounced "Furikuri" ("Fooly Cooly" in English), not "eff-ell-cee-ell." The letters "FLCL" are a romanization of the four Japanese Katakana characters that spell the title. "Furikuri" is an oft-repeated term by the characters but its meaning is never specifically explained.
GAINAX Studios, a cartoon production studio in Japan, made this as "a break" from normal anime, which fans of the series use as an excuse for the insanity that occurs. In reality, the show, despite having a plot, is really just crazy.
Director Kazuya Tsurumaki personally oversaw the English dub in America. He was very insistent that the voice actors/actresses from the English dub had the same "essence" as the Japanese actors/actresses. He said he was very pleased with the characters for the English dub, and was especially pleased with voice actress Kari Wahlgren's Haruko.
In the second episode, Naota tells Haruko that the reason his dad acts so strange is because "He wrote an 'EVA' book a while ago". (in the English version, "He wrote a book on the deep mysteries of 'EVA.'"). The show he's talking about is Shin Seiki Evangerion (1995), a hit series made by the same animation studio with some of the same staff, and that line is a tongue-in-cheek reference to the confusion the final two episodes caused when they first aired. The director and writer of this show, Hideaki Anno, is also the uncredited voice of Naota's cat Miyu-Miyu.
Mamimi is only once shown in the process of setting fire to anything, even though she smokes almost constantly. This is in Episode Two (FireStarter) In the rest of the series, when she starts a fire, she turns away from the camera in such a way that the flame cannot be seen.
Hideaki Anno made the Daicon III and IV animations while he was in college thus was born Gainax. For this reason Haruko appears in a scene with the bunny suit flying in a guitar while she screams that she is Daicon V.
The creation itself of FLCL is an amazing work of art that draws techniques from classic American literature and modernist ideas. To fully understand the depth, the audience must be familiar with literary techniques and purposes. The characters, social interactions, and plot elements are all metaphors overlapping each other to cross-hatch the bigger picture that is, coming of age. The finer pieces are up for interpretation. FLCL creates analogies on a variety of social fronts. The series uses sexually ambiguous imagery similar to create humorous themes as The Ren & Stimpy Show (1991) did in America during the early 90's.