Haha, good questions. Graphene is actually not a good conductor unless you dope it, by adding or removing charge, but when doped it is very good conductor in terms of carrier density. Have a read on the article i posted the other day about graphene, it may answer some questions.

As far as ceramics go, it is possible, you just need to create a certain lattice structure with the compounds of the ceramics, but not all material can have the property of SC. It's all about the lattice structure and elements used.

Good questions :p