You can play as anything you'd like; remember that characters don't always have to be 100% effective. That's what a party's for~
The world will be fleshed out more on the OOC as I don't have the specs yet. But do know we will be going against some machinations at some point.
I'm not sure about ARIES yet, really. I think I'm going to have it that everyone's an equal and they kind of vote on things via a "round table" kind of system, where everyone's opinions are taken into consideration. Not sure yet