Quote Originally Posted by Squid
1) Is there a condition that would let me test the (net) population growth rate in a settlement? (There's one for tax level and one for health)
No.
Quote Originally Posted by Squid
2) Can what advice is offered be modded? I know the messages for a particular advice trigger can be modded, and custom messages & advice can be created, but not if we can mod the game so the condition AdviseBuild is set differently.
You would need to modify the advice trigger.
Quote Originally Posted by Squid
3) What does a general have to do in order for the NoActionThisTurn condition to be false?
Not sure. Definitely can't move. Don't know if construction of a building or unit counts.

Quote Originally Posted by Squid
4) Is there a way to change/set which building can and cannot be destroyed?
Partial answer: Any building name prefixed with "hinterland_" is indestructible. Government buildings (core_buildings) are also indestructible, but there's no way to mod this.