RE: Single vs. Dual Conversion Receivers
I don't understand why you want to know the answer to that question, or how it's related to your airplane.
As regards your airplane, order a reciever and crystal that match your transmitter.
As regards the "dual conversion" and "single conversion" feature, it is a very short description of what the receiver does with the frequency of the transmitter signal, before using the signal to generate servo deflections.
Good luck with your plane!
Dave Olson