2) On which cameras (apart from the polaroid SX 70 and the series 600 - these cameras do not appeal to me much) can the films from Impossible Project be used?
That's it. SX70 film can be used on Polaroid cameras that accept SX70 film and the 600 series film can be used on Polaroid cameras that accept it, including the SLR680/690 cameras. These are called integral films and to my knowledge there is no interchangeable film back to use them on other cameras.
Only the "packfilm" type films (now manufactured by Fuji) can be used on the cameras that offer appropriate backs.