A question about the show Torchwood?

Jack doesn't even really know why he's immortal. I mean Rose did it, but it didn't get a big explanation. Jack and Rose didn't even talk about it when they met again, weirdly. Gwen and Ianto sort of met the Doctor in Journey's End so they know what he looks like and what the Tardis looks like. I don't know if they know the Doctor is Gallifrian, or killed off his entire race, or that he changes bodies. They know what's in the Torchwood records-- the body changing I recall the other Torchwood heads knew. When Gwen was musing about the Doctor in Children of Earth, I don't think we're meant to think that's the truth, that she really has a clue about his motives.