The purpose of the matte box is to keep light from shining directly on the lens, and forming lens flares. While they look neat, they are considered bad form... The matte box is mounted on the bar coming out of the front of the camera. It moves forward to allow one to rotate the lens turret. (to select one of three lenses)
The Tachometer displays the camera speed in frames per second (well, its actualy Bilder/Sek). The body of the motor rotates to allow one to change the speed (the motors are interchangeable, and there is a constant-speed one also). This camera will go up to about 60 frames/sec. The camera will also go backwards, though the normal procedure for shooting in reverse is to hold the camera upsidedown, and flip the film over later (make sure you use double-perf film).
The footage on the magazine is only good to the closest 100 feet, while the counter on the camera body only goes up to 115 or so. Which means every 100 feet reset the body counter, to take the 15 extra feet into account.
The Torque motor keeps tension on the takeup reel, to make sure the film rolls up correctly.
This is a particularly impressive lens... Its a 400mm telephoto lens, which in 35mm terms is about 1000mm.
Ominous looking critter isn't it?