Swapping the archer with the wheel or horse in a way that leaves a gap between them makes only the horse move with carriage commands, the wheel stays wherever it was when you swapped.
I only seem to be able to attack my own units. Can't target the goblins. Here I've moved the archer and selected attack, but instead of targeting the goblin, its targeting one of my own units. Same occurs with the swordsman.
I've tried clicking, dragging, and dropping them into the large rectangle under my deck's name but they just land back with the other cards. I assumed that's how you do that.