for rust ,just sanded the area and touch up with paint . as far the paint goes any fingernail polish will be fine or go to a hobby shop and pick up some model paint . they all come in many colors so one should match . For servicing the freehub you'll need a chainwhip tool and a cassette locking tool to remove the cassette from the body . Cost of the tools around 25 - 30 at your LBS .