At any given moment, there are roughly six astronauts living aboard the International Space Station (ISS) and the thriller follows the actions they take after receiving distressing information from Earth that threatens their missions and their lives.
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.