Yes, we were only trying to answer the question for which we have an answer (or I in any case), the one about the result of interrogations. In the case of returning rescued crew and them being called POWs, I´ve never heard a way to return them, presumably such feature has not been implemented, would be a good sugestion to make (improoving relations, etc).
On the subject if intelligence gathering is linear or probabilistic, I am not sure either, I have the impresion of rescuing hundreds of lifepods without gaining intelligence, but I really didn´t counted them preciselly and it was sometime ago and memory might fail me.