Dee has to blow up the ship for this right?
Is there a plan to have Dee in some sort of mini device in Erra's room when you recruit her or does she die in the explosion?
Dee will survive, in fact Erra's immediate reaction after you and her fend off some Reaper drones and tell her you should get back to your ship is something along the lines of "What are you, crazy?! We gotta go save Dee!" before she runs off to save her AI.
I'm not sure exactly what'll I'll be doing with her after the quest, bur her and Erra are going to come as a package, as in: no Erra without Dee. She might be mutually exclusive with Hand-So as a shipboard AI, or she might hang out in some device Dee can carry around, or my favorite idea: a sick military robot body.
Keep in mind that if Dee gets a robot body it'll be 100% asexual.