My anode is on the back of the propeller, but as it is one of those very expensive feathering ones it is designed to take it - but you may find one that goes on the lock nut.
As to the copper braid, they were made up by a mate and I think it came from an electrical wholesaler and is used for earthing. Seem to remember it being about 15-20mm wide. And, yes the idea of the solder was to make a washer for the bolt/nut. It also had the advantage that it could be moulded to shape across the coupling to avoid upsetting balance - not that I think it would be a serious issue.