With both wings swept back as yours is, you can put the CG as far back as the rear vertical cabane.
The plans call for it to be about a half inch forward of the rear cabane.
You can download the plan from here free.
http://www.outerzone.co.uk/plan_details.asp?ID=1971
The belcrank system of one servo for both ailerons works well if done correctly.
I have one with a Spektrum DS 821 servo driving the two ailerons. Works fine.
I also built one with two servos buried in the wing so each aileron had it's own servo.
I used Futaba 3004 servos for that. personally, I wouldn't go smaller on the servo, but that is just me.
The Aero is pretty fast and the one I built for a friend has an OS 95 in it.
I would not have recommended that engine, but after seeing it fly, I'm a believer. it's a good combination.
First picture is the one with the two servos buried in the wing.
The servos are attached to a 1/16 ply plate and held in with screws.
The second picture is the one with belcranks and a single servo.