It appears that if you can unscrew the black trim ring around the front lens element w/ something like a rubber stopper, you should be able to get the front element out. If you don't have the rubber stopper, I've managed to get the trim ring off other cameras by placing a very small screwdriver into one of the incised letters on the trim ring at an angle, and giving it a few gentle taps w/ something. It should be easy to get off.
Please keep in mind that the fungus could be between cemented elements, assuming that it's constructed that way. If that is the case, you could take the camera and set it facing a light source (like the sun) for a few days to at least stop any further growth of the fungus.
The top will have to come off to get that viewfinder cleaned. It looks like the knobs on top are similar to Agfa folders and many other cameras, looking at threads on how to CLA those should give you a clue about how they come off. I don't think you need any special tools, just some good screwdrivers.
I once had a 6x6 folder w/ a Dacora lens, pretty sure it's a 3 element. That folder took very sharp photos when it was stopped down.