All those suggestions are of interest to someone, but not necessarily to everyone, and would only be temporary for the duration of the event.
How about adding something to the game that would be permanent, and may be appreciated by everyone?
I was in a discussion last night with some fellow slashers, and we came up with this:
Since the chat log already shows you when you have received a new level in proficiency,
why could it not also show what you have gained when completing a quest?
Example: Treasure pest reward is +1 to 2 Item Slots, +2 to 5 Stat Points
Notification could read ''You have just earned # Item Slots and # Stat Points''
It should only be shown to each player individually, as is the prof notification
Bragging rights would increase, of course