A person who struck someone in the back of the head tells someone afterwards that he could feel it cave in, but I didn't notice that in the scene where it happened, so it can't have been that graphic. The struck person's head is intact seen from the front.
YES, a parent dies!!! By strangulation. We don't know the person's children, but the person mentions them several times and misses them (referring to them as "my girls").
No; a female character tells that her female partner cheated on her with a woman. It IS said outright that it was a woman. Besides, it happened before the events of the movie.
There's no hospital and no doctors or nurses, but there is a scene where someone who's been badly injured is lying on a bed/stretcher/operating table with some medical equipment nearby. I don't remember details.
The worst thing is when someone is killed with a drill (to the body, not the head). Still, not too bad. The drill goes through fabric, so we don't see the skin.