Re: tying flies
The electric fence wire is probably way too thick to be of much use. The solder is likely too big, but some is small enough to be useful for fly tyers. However, lead wire is generally used as weighting wrapped directly around the hook shank and then the fly is tied over that. Lead wire isn't all that strong and thus isn't the ideal rib.
You probably do have some ideal ribbing sitting around the house, you just don't know it. Find that corded old appliance (radio, iron, hair dryer) you just haven't yet gotten around to throwing out. Chances are that cord is made up of many strands of pure copper wire that should be nearly ideal for ribbing purposes. If you can find such an appliance, you'll likely have enough wire for years.
To keep Steve and myself out of trouble, I suppose I should point out that the appliance must be unplugged before any separation is done to any of its parts.