Well I did the final mission and lost one crew member and my entire staff save the doctor(though I don't know if they can be saved, I sure fucking hope so - I want the two engineers). It was weird because the chef and someone else was clearly alive within the cutscene. I was so amped up too because it looked like it was one giant close-call, but then they showed a dead teammate I never even used for the mission(Merlon) on the floor for 2 seconds.
I am going to guess when someone gets killed off screen it is because you are taking too long. This may be the case for crew, the defense team, and maybe the 2nd specialist. When the specialist gets killed it is probably because s/he doesn't have the correct skills. Thane got headshotted, Tali was fine(I was so worried, gawd this game is tapping into my emotions). Probably will have to work on it.
Also I am a little annoyed that they don't show off everyone until you are standing before the path for the final boss. I wanted to see 11 dudes wreck shit together in the cutscenes.
Another thing, while I am hoping for a "full-cast" save, I get the feeling almost no one is coming back. It seems like ANYONE can die(even Shepard?) and that adds a lot of variables which can make voice acting difficult.
I used Legion, Grunt, and me(Soldier, with anti-armor/health bullets for the whole team) the whole time. Team is sick and keeping Harbringer off you. Garrus and Meranda were my fire team leaders. Then I went Tali and Samara for my specialist