My recommendation on the wire extension is standard single conductor shielded audio cable. This is a high-impedence pick-up and has a high loss-per-foot ratio. Simple copper wire will work, but using shielded wire, such as used for a mono microphone cable or stereo channel cable will work better. Do not use antenna wire, even though it meets the requirements of single conductor and shielded. It has built-in resistance that would contribute to signal loss.
Worst case, go to Radio Shack, buy a audio or video signal wire that has a single RCA pin connector on each end and lop off (discard via wire cutters) the connectors. It will not matter which lead on the pick-up side you use for conductor or shield, but if the wire in your device is similar, connect shield to shield and center conductor to center conductor.
*JC*