i havnt updated my old screen here so its hard for me to see detail...but the frame looks to have a large rebate, big enough that would take the thickness of a glass plate. So it appears that if you put sheet film in the wooden holder first and then the metal frame the film would be loose, unless you put the frame in upside down. if you put it in upside down it would not be in line with the GG but would probably still take OK pictures because the DOF would probably cover. However, using it properly, for better results, it would be designed for the glass to be placed first in the wooden holder and then the sheet film on top of the glass and then the metal frame to hold the sheet film (i said it back the front before, meaning that the film placed first in the metal frame and then the glass plate in the metal frame then the whole thing placed in the holder).
thats how it looks to me atm, if however the frame does fit the film and hold the film flat (not placing the frame upside down) without the film being loose in the holder then it is a holder just for film. just that the rear septum of the wooden holder doesnt look that flat to me on my screen so it looks like it would be designed for glass plate...either way you are able to use film in these holders.
NO, the shutter is air operated, i mentioned oil because it is a common mistake that people lube the pistons with oil and it destroys the shutter. if it is working then it is one of those things best left alone, if it needs servicing then someone that is familiar with them is best