With regards to napalm, i use it quite a lot, especially when fighting against infantry in co-ordination with our armoured forces - napalm some command points, which gives your armour time enough to move in and secure it from enemy infantry.

And obviously burning down forests. Whenever i'm lounging around with my arty at the back i tend to burn down the forests near me so that enemy airborne can't drop in and pay me a visit.