StrutOutWithYourGutOut

Hey! I'm a newer player and had a game today where my opponent was attempting to make a pile-in-move around gnoblars. Their special rule states that after a unit makes a move within 6 inches of them, you can roll to determine of mortal wounds get dealt. My opponent felt this didn't apply to pile-in-moves. Also, can someone tell me when I need to announce that my Ironguts will use their "Down to the Ironguts" ability. Again my opponent felt that I had to announce it immediately after my Ironguts fought as opposed to before we entered the strike-last phase. The ability doesn't clearly specify when this should happen.