I was told the wire coming into the house was an antenna for a ham radio.
Before we moved in, we had the breaker box redone, so it's no longer a fuse panel.
as for the GFCI, we had an electrician do it simply because the outlets had only two prongs. I needed something with 3. And we cannot afford $10,000 + to rewire this house right now. So GFCI was the only alternative for the moment.
I don't notice any difference with appliances being off or on - at least i haven't yet.