The version currently available is the director's cut since it is the version Friedkin himself approved with his own editing decisions. If the lost scenes were to be inserted (and work on doing so is in progress at the time of writing), then this would effectively be a 'Writer's Cut', since it would contain the scenes Blatty wanted in the film.

Paul Davis recently received news that the spiderwalk will appear in a new cut of the film to be released next year. So, it would seem, yes.

Its difficult to tell. A four-hour TV mini-series of the original novel has been proposed but news of this is sparse and unreliable and as far as I know the project is languishing in development hell. I've also heard some rumours that the project was scrapped altogether. If any news on it comes to light I'll let you know.

Interiors (that is all indoor scenes) were all shot in New York's Ceco studios. Some scenes were shot in Hell's Kitchen in Manhattan Island. However, most exteriors were shot in Georgetown. The MacNeil home can be found in Prospect Street, a little further from the famous stairs than in the film since the actual house is only half the size of the one in the film (An extra wing was added while filming in order for the house to be closer to the stairs. Other scenes were also shot at Georgetown University (visit their site at www.georgetown.edu).