[spoiler=Hoshido route]It's a CG cutscene death so I'm pretty sure Elise dies no matter what, same with Xander given that he gets suicidal afterwards, dunno if you can spare his subordinates though.
[spoiler=Nohr Endgame]Takumi is the final boss (possesed by something, dunno what's up with it) so he's toast no matter what.
[spoiler=Question about both routes]I saw Camilla as a boss in some streams, but she survived the battle, any way you can screw up and end up killing her? Hinoka is a boss in the Nohr path too, but Kamui spares her and her subordinates, is that scripted or it's dependant on some action you take in the chapter?