If the audience is ready to watch ambitious films by driven, eccentric foreign directors, then it also may be ready to see films about those eccentrics as they direct. That theory, at least, was at work when Werner Herzog's long-delayed "Fitzcarraldo" finally hit the screens early this month; along with that film came Les Blank's "Burden of Dreams," a documentary that followed Herzog as Herzog moved a 320-ton steamboat over the mountains in the Peruvian jungle and suffered through the troublesome five years it took to finish his film. Though neither the film nor the documentary has received raves, a similar offering will accompany Rainer Werner Fassbinder's final film, "Querelle." That film, in fact, will be preceded to the screen by a documentary about its making, "The Wizard of Babylon," which has just been acquired by New Yorker Films for a planned release early next year (its originally scheduled debut at the Chicago Film Festival next week was canceled). "Wizard of Babylon," though, almost didn't make it at all; part of the film includes a 12-minute interview with Fassbinder conducted a couple of hours before his death last June. The director's mother, Lilo Eder, objected to portions of the interview and obtained a Munich court injunction against the film. The injunction has just been overturned by a court of appeals, but only after a compromise was reached between Eder and director Dieter Schidor, who agreed to cut about a minute of material. The director also agreed not to show the film on any television station (except in Great Britain) until June 1983; with those concessions, the documentary has just been granted its release. In this country, "Querelle" itself will follow "Wizard of Babylon" into the theaters early next year.