I'd say everyone else here pretty much covered it. If you got Cliff in your combat party, be sure to stay away from Might Hammer while in the Lava Caves. Great attack, yes, but fire elemental. Don't wanna wind up healing your enemies, do you?

As for optional characters to take along from Elicoor, Nel' always a good pick, IMO. Roger can be decent. Albel's also another rockin' choice. Again, though, it's all a matter of preference.