1. I believe the new viewfinders, which includes both the waist level viewfinder and the full frame prism, can be used with any of the H bodies.
2. Why would Phase "want" to reverse engineer their backs to go on an H3. An H3 is the same body as the H2. The only thing you cannot do with an H2 is mount the new H Series Digital lenses like the 28mm. Moreover, even if the camera could be reverse engineered to accept the P45 and the H Series Digital Lenses, the Phase back still would not be able to make effective use of these lenses because the optical correction is in the Flexcolor software. Unless, of course, they also reverse engineered their files to open in Flexcolor. [G]
1: if thats correct, its good news for H2 owners who could have the full(er) frame finder.
2: I think its more complicated than that - there is much more camera:back dialogue going on, shared power sources, etc than before - its an integrated package, and thatis what cuts out putting your P45 on an H3. Can't see why Phase couldnt work that out to integrate, but I'm no expert. The lens corrections can always be applied afterwards - like in DxO optics software, and there really is no reason why Phase couldn't add lens correction modules to C1 if they wanted to. there's not so many lenses/MF cameras out there, so it shouldnt be that hard. If they are bringing out an integrated package with Mamiya anytime soon, then they will have to offer this to keep in the game anyways.