Battery cables

A lot of what you're asking we can't answer without seeing it. The fat negative battery cable always bolts to a paint-free bolt on the engine. There is usually a smaller wire that bolts to a paint-free bolt on the body. Either one can be moved to a different spot. In fact, it must be if the area is rusty.

All you need to worry about is the new cable is the right length and it has the extra smaller wire. If you manage to find a cable made for a really old car or tractor with a 6 volt battery, that will be fatter and will work fine but you'll be paying extra for something you don't need. Your car has side post battery terminals and I don't think they ever made those for 6 volt systems.

I don't know what you're asking in the last question.