RE: 4 Aileron Servo Set-up
There are several methods that have been used succesfully for years prior to the availability of Matchbox type devices that have served well.
What type of servos wil you be using? Programmable servos such as Hitecs 5945's would be an excellent choice IMO. There would be no need for any ancillary equipment with these.
Will you have additional channels available for mixing aux channels? Will your RX support the additional channels?
Do you intend to use two channels for the ailerons?