You did not say how long you have been out of the hobby. But things have changed a lot in the last 10-15 years..
The Hitech 485 servos will be just fine as individual aileron servos for the 4star40.
I am not familiar with all the feature of the Spektrum 6 channel, None the less using a Y harness will be able to work just fine but there should be no need with that radio set up. You would have more versatility using the available functions of the radio for two aileron set up.