I'm only halfway through the book-- but this is something I've thought about a lot... It seems convenient that Eo dies, Darrow buries her and gets hanged, then the team is all ready in the background to swoop him up. Or maybe they were just waiting for the right moment over a long period of time?
Also-- I wonder if Eo had any idea about the bigger plan! Part of me thinks she did but also I think she would've told Darrow.
I've actually never really payed attention to how convenient that was, but now that you mention it, wow that certainly was! I'm a bit hazy on the events around the first book but I think it could be very possible that Eo had sacrificed herself with the belief that Darrow would act upon it. In my opinion, she seems like a person who would go that far for things she believes in.
I want to believe that she felt like she had to inspire SOMEONE to defy the system, and that's why she had to make the sacrifice. But I like to think that she didn't know just how big an impact she'd have. For example, later in the book, Mustang is humming her song. She broke through color barriers with her statement.