I doubt you will find an ign company [ Pertronix, DUI, MSD, Accel, etc ] that will recommend carbon leads. They are CHEAP, which is why they were used. They were also unreliable.
Use any spiral or heli wound leads of your liking & you will be good to go.
Carbon leads are good at noise suppression but also give up some of the ignition power. I would use spiral core metal if buying new for a performance ignition. My own preference for a supplier is Magnecor, although I have examined Firecore wires and they're great too. Just don't have as many plug boot options.
I would not. Being grease, it will attract particles in the air & over time that could become a conductive path to bleed off spark energy. Clean the spark plug insulators from time to time with thinners, acetone, etc.