You can now earn bonus reputation for your first dungeon and scenario of the day. You can select which reputation you choose to champion by selecting it from the reputation panel on the character screen. When you queue for a dungeon or scenario, the UI will remind you which reputation you are championing and allow you to change the reputation from there. (You cannot change that reputation once you are in the dungeon or scenario.)
No, no you can't. I select the bonus rep button, select the rep i want to increase, write down the starting rep value in my little notebook, and low and behold for a second day in a row, it doesn't increase. For either dungeon or scenarios.
This must be what you call intangible benefits.