Sevro is another key character. He is a friend of Darrow. His unique skills and personality contribute to the development of the plot. He is quite a memorable character with his unorthodox ways and fierce loyalty.
There are military commanders on both sides of the conflict. I can't recall all their names precisely, but they play important roles in leading their troops.
Definitely. Red Rising falls into the YA category. It has adventure, romance, and a focus on the development and struggles of youthful characters, which are common traits of YA novels.
It's a novel within the Red Rising universe. It's expected to be full of action, adventure, and political intrigue. It will most likely build on the storylines and characters from the trilogy, and might introduce new elements to keep the story evolving and interesting for the readers.