This is my first post to apug, so let's hope this works.
I collect rangefinders, and shoot with them.
And fix them.
You can clean gunk on the chrome by putting a small dab of toothpaste on a piece of paper towel, and rubbing hard. There's enough abrasive in toothpaste to do a good job of cleaning chrome, but not enough to damage it. Remove the residual toothpaste with a damp piece of paper towel.
You image through the viewfinder looks correct. I assume the mesh is something outside the camera. I see framelines, and the rangefinder-spot in the middle.
The four-element f/2.8 lens is decent, and should provide adequate sharpness for enlargements when stopped down to f/5.6 or smaller.
Be careful about the pressure plate: People often slide the back of the camera too far down, causing the sprockets to scratch the pressure plate. Those pp scratches will scratch your film, so you'll want to buff out any scratches in the pp.