A few more odd little questions

Another couple of (I imagine) easy ones: First, when aligning the batty connector before epoxying it down, what is the best way to ensure it's straight? also, can you modify the outer edge of the connector, say adding a keyway to the hole and dropping a bit of solder on the connector to fit? also can I solder the negative battery connector wire to the exterior of the connector, instead of the inner edge? Second, what is a good insulating material I can add over top of my wires, parts and such once everything is epoxied and soldered? I see alot of mods with a black, plastic like material covering the inside wire areas. It looks like plumber's dip, or maybe melted electrical tape to me.