Well the cover I'd of just left it go after a good cleaning and a bit of jbweld to seal against water, these things are so cheap it's not even worth trying to keep it pretty looking. That screw might be found on an old bicycle if you have one, the thread is the same as what's normally used on a crank arm for the pedals, it's the one holding the arm to the shaft (bottom bracket) with the gears on it. Those are just about always going to be a standard hex head bolt, so you can remove and install with a (usually) 14mm socket wrench, way better than a flat head screwdriver. Bevel gear is correct.
The metal shavings are unrelated to the clutch, often the chain rubs the metal under the cover, usually the section nearer the front of the motor, that creates shavings that get stuck in the grease inside the cover, it's kind of normal and impossible to avoid unless you go and shape it down with a dremel. I would give the entire chain, drive gear cover, and rear sprocket a good cleaning with a rag and solvent to get the metal off it, that stuff will get into the chain, and on the other meshing gears and act like sandpaper and rip up the gears and chain, wearing them down and 'stretching' the chain, which furthers the wear on the gears more.
