Usually buzzing is associated with stray voltages which might be present without sufficient grounding. Double check that your black wires are securely grounded (earthed - to some people). The scraping noise of the volume pot is usually associated with some corrosive build up. Get some contact cleaner and spray some of that on/in the control pot and turn the knob back and forth a bunch of times... of course do this with the guitar completely unplugged from any power source...