On Betrayal at House on Hill, once haunt is revealed and everyone knows their parts do both sides then reveal what their ultimate goal is? Such as I , the traitor, have to release a demon and kill you all. And do the players then say ok well we have to collect this item and do this to win?
When the haunt starts the new rules are only known by the side that they are for and not everyone.
The traitor generally leaves the room to read the rules that apply to them and it will give them some idea of what they need to do to win and what their former friends are going to do. At the same time the rest of the group will read their rules and it will give them some idea of what they need to do to win and what the traitor is doing.
The only time this changes is when a haunt lets a traitor convert other players then that player will also get to read the traitor rules and they will now know both sets of rules.
No. That's the whole point of the two different books. If both sides were getting the same set of information, you could just read one entry for both. Note that some of the information might be in both books. So if you're the traitor, then not only do you not know the players' information, you don't know if the players know some of the traitor's information. And if you're the players, not only do you not know the traitor's information, you don't know if the traitor knows some of the players' information.