So far, I've always had to vote on the peace as a ruler, like it will pop up and make me do it if I ignore it. I am aware of other players saying they missed the notification and it was resolved without them, not sure if it a player kingdom or as a vassal though. People have said they "hear' the peace offer but don't see the emblem. For the second part, yes the only time I've payed tribute in my current game was to the defeated Khuzaits, meaning just their ruling clan and mercs, even though they pose no threat. I think this is because thier war score makes them so aggressive because they have no fiefs compared to field power. They of course declared war very soon but I haven't seen a peace proposal for them again in a good while. They are basically fodder now and there are just too many of my parties for them to even raid. Bad deal for the mercs though...