re: 'Four Devils', here's hoping it's real, but like any such rumour, I'll believe it when I see it. Sadly, signs point to it being a hoax. Janet Bergstrom made an interesting documentary on 'Four Devils' called 'Traces of a Lost Film' which is on the Masters of Cinema (UK) DVD of 'Sunrise' (may be on other releases too), which left me itching to see the film. She's apparently involved in the recovery attempts, and I wish her every success, if there's anything to recover.
The best version of Faust currently available is indeed the version from Masters of Cinema, in a two disc set which includes the version previously released by Image/Kino/Eureka from the 'export negative'; PLUS a previously unknown German 'domestic' version made up of better takes, and sourced from higher photographic quality materials. It's stunning, and I'd highly recommend it. Great commentary, too, from David Ehrenstein and Bill Krohn, and the Timothy Brock score is a perfect fit.
Skylark: Murnau's 'Faust' is adapted, sometimes freely, from Goethe's 'Faust', which in turn derives from Marlowe's 'Dr Faustus' (and which in turn derives from various German 'Faust-books'). There's not that much Marlowe in the Murnau, or at least not much that can't be traced back to the German source materials. Goethe greatly expanded and reworked the material in line with Enlightenment sensibilities. Some of the knockabout comedy in the Murnau has been ascribed to Marlowe, but Goethe features his share of low comedy too. The Faust legend is pretty fascinating in all its forms and treatments.