I was just wondering if you open a door in skirmish, does your interaction unlock the door, or does it open the door?
Also, later in the skirmish game, with my IG-88 I would attack an enemy. When I attacked with IG-88 he either had the option to take damage or draw a card from the top of his deck and discard it. Now what happens when your opponent doesn't have any cards to put in discard pile? The way I see it is that they would take a damage since there aren't any more cards to draw.
The locking/unlocking mechanic only would be possible if a Skirmish rule stated it specifically. By default, a door always starts in the closed, unlocked state, unless the mission rules (Campaign or Skirmish) say otherwise. Thus, one interact action will open those doors.
And yes, a player with no command cards in his deck cannot discard cards to avoid one of his figures suffering strain. The figure must suffer damage instead in this case.