As for customizing characters, supposedly the game will employ a new stat system that allows you to customize the play style of each character, inputting data to balance its speed, strength, etc. to the player's liking. Also, it is said that each character will have an arsenal of moves that the player may map to the character, allowing for even more customization.
While this is all a huge rumor right now, we sure hope that it turns out to be truth.
[Thanks Thousand Dragoon Link!]