I took a Joss Stick and set it up with the Ultra Stick quad flaps. I recall I used 7 channels (everything except gear) on my JR 8103 so I would say you need an 8-channel radio. The Ultra Stick manual, which you can download from the Horizon site, shows the programming for several radios, including a Futaba 8-channel. I believe you do not get all the functionality with a radio of less than 8 channels.

On your 4*40, make the flaps about 8 inches long and the rest ailerons. You'll need 4 servos in the wings and lots of extensions. If you want the full effect of air brakes, you'll need to widen the controls to 2 1/2-3 inches.

In addition, cut off 1 rib on each side, add an inch to the rudder and 1/2-1 inch to the elevator. The plane rolls better, doesn't land any differently and is generally better in aerobatics.