I have Kurt Helborg in combat. Dmg is assigned and then it is applied. In the action window after dmg is applied, is Kurt still considered to be in combat? And thus able to play a bunch of 1 cost tactics for zero each?

According to the FAQ:

"Damage is applied and its effects resolve. Units and legends leave play if they have damage equal to or greater than their hit points. Burn tokens are placed on the capital if necessary. This is the end of combat. Units are no longer considered to be attacking, defending, or participating in combat."

Thanks Horatius. Your help is greatly appreciated.