The main villain cast is going to happen one way or another. The whole story of Dissidia is Light vs. Dark. Hard to not have bad guys in a series that is famous for their bad guys.
As for DLC, probably a la DOA5A for Arcade version, unlockable from a tile perspective and some kind of paid/point purchase for console. They have outfits they can pull from 012 or even their promotional stuff like 3rd Birthday Aya Brea for Lightning. For the games with sequels and prequels there are also outfits they can use. The options are there and there is no doubt in my mind we just haven't seen them in the videos shown.
Ramza actually looks how I imagined he would look, pretty much like any concept are that you can find of him (minus his face, I'm really hoping his face ends up good in photo realistic mode). BTW watch him get Stone Throw, I will laugh so damn hard if he gets it. Probably upped him to Holy Knight status.