Burning buildings would be easy to do. Spawn the fire objects and place them on the building, and then set them to dissapear once water has been on it for a certain amount of time.......

I can also help with modelling should you need me.

You should also add a failure condition, if the fire consumes the whole building it is considered as destroyed, add a random chance for the fire to jump within a set range (this should simulate the protocol for spraying close by objects with water), add a random chance that a point can re-ignite.