The scar "could" be a pecking wound. I had that happen to one of my hens this year that freaked me out until I figured out what it was. My tom latched on and was dragging her around causing an ugly looking wound. I really can't tell from the picture, it's just a guess.
Sorry but I don't know what could cause a swollen head either other than a possible sinus issue. Is he showing any other symptoms physically, odd behavior?