Do when revealed effects happen when things are added to the staging area? Like a treachery, or a location with a revel effect... ?

Read the cards carefully when it instructs you to do this. Sometimes it will say "reveal and add to the staging area" and sometimes just "add to the staging area." If it says reveal and add, any when revealed effects have to be resolved. If it just says to add them to the staging area, when revealed effects are not resolved. If a quest card is having you add enemies or something sometimes you can avoid nasty effects this way.