The full list of roles and abilities is the last post of the game, only made public after the game has ended. This is one of the primary differences between forum Mafia and Werewolf-like party games. This is also what makes it fun
. And besides, knowing the roles in advance would mean that a simple role call in the 1st 5 minutes of the game would be enough to end it right there and then.
For reference, you could read the previous 3 games' role lists, they're bound to help figure out a pattern, the way things work.