You can have as many characters as you want, actually. KChan here has like... five. This of course was because we were active, and we wanted to progress the plot.
For each character, just register a separate account with the username being the character's name.
You can absolutely be an Elariel. We currently have one Elariel, but I haven't spoken to her if she wants to come back. Either way, just because there's someone in a Great House doesn't mean you can't make characters there. You'll just get more people to interact with that way, which should make things more fun
Also, note to everyone else, you can also create your own noble house, including Great Houses. We aren't copying Mistborn 1, you know, so if you wanted to lead a Great House, you're golden. Naturally, you'd have to be more active to be a Great House, because they are scheming all the time.
Here are the current House standings. There's Venture and Elariel in their familiar spots, but there are some new ones, too. There are also plenty of empty slots for Great Houses. In fact, since the person controlling Ewing isn't coming back, that one won't be on the list (or we can rename it, giving it to another character/player, and be essentially unrecognizable as "House Ewing"). If the character Azoth Urbain doesn't come back, then that House doesn't necessarily need to be there, either.
Here's a cheat sheet of information on Houses. Also, in the forum "The Back Parlor" there's info on all the houses, Great or minor.
Don't be intimidated by the stuff that is already there. Anything you want to do, you can do it.
now, is this happening on this forum? or at that link up there? If this is happening I am so game it ain't even funny.
Well, since the Mistborn Forum RPG never truly progressed very far, I humbly suggested to use that site. Mostly because it has all the framework you'd need, plus it's a really pretty site. So unless people have a major objection, it's going down here at
http://z3.invisionfree.com/Mistborn/index.php?act=idx