G'day Mate,
You may even try a 15x4, overpower this plane is fine, but DON"T overspeed it, or any good 3D aircraft, they are not designed for all out speed.
As for fueling, I personally don't use fuelers, because they will eventually leak, not fuel, but air, because it is on the suction side, of the carby, & that will cause mixture problems, so I use fuel dots, use the third line, & put the fuel dot where you were going to put the fueler, all probelms solved.
Those servos will be fine. If you need more power it will generally be on the rudder, suck it & see.