diplomatic options

I think there is an extra layer that can be added to the game that would create a sense of strengthening and developing relationships between civilizations that can be achieved by copying the espionage mechanism and adding a new unit: the diplomat. Diplomats are civilian units that can always...

Is there a notification when one of my City States are under attack? And how do i join that war without incurring the whole worlds wrath until the end of time? Is there any other non-military way of helping i have missed somehow or is this it... there just are no features regarding City States...