As you'll soon find out, the extra cable is there so you can hip or chest mount the control pod and battery. Your arm will tell you when it's time! It's a beast to swing out of the water for any length of time. As for settings, I recommend you hunt in discriminate with a setting of 1 or 0 until you learn your countries coin sounds. With all the iron you say is present you will notice that your background threshold will null and then change pitch to a very low tone when you go over iron. It will stay low toned until you pass the coil over a better target. Don't let the tone discourage you as there is nothing wrong with the machine, but it can be annoying. If it bothers you pass your coil by your scoop or a coin in your hand to bring the threshold pitch higher. It will stay there until your coil goes over its next piece of iron. I don't believe the newer batteries can be overcharged. I charge mine for between 10-12 hours battery pod should feel a little warm when fully charged. Happy Hunting, looking forward to your results.