Well, you say "one or two" new PCs. . . if you lean towards two, I'd be interested in joining as well.
For the mythic persona, I'd be interested in stating up the briefly mentioned Ehrero Khan, if you don't already have a firm idea of what he was. I'd probably stat him up as an Orc Paladin. . . a zealot conquering in the name of his dark god.
As for my character. . . well it's long been my
dream to play a goblin in one of your campaigns. Or, well. . . it was an idea I had once before, five years ago.
I thought that there might have been a very small community of goblin prisoners/slaves in the city when it was sealed. Over a thousand years it has continually declined until only a single one remains in the city. Long since assimilated into dwarven society, he knows nothing of being a goblin. The dwarves still mistrust him on an instinctual level, although none have lived long enough to remember the crimes of his people.
If the goblin idea conflicts a little too much with the established information, I would also be interested in one of the dwarven citizens, pulled into whatever events follow by mere dint of being present.
Either way, I'd probably go with a striker of some kind or other. My theme would be an exploration of racial identity and stereotypes. The goblin would be unsure of what his own race means, while the dwarf might be an outsider in his own people.