I'ved used rossi engines in the past but have found they flood very easy in the inverted position. I've had times at the flying field that I can't get them started. I'll remove the motor at home, mount it on a test stand upright and it starts on the first spin. The o.s. engines I have no problem starting inverted and don't have the tendency to flood as easily.
I'm not familiar with the byron f-18 but on the other byron jet kits they are set up with ailerons separate from the elevators. The byron jets I fly, flaps aren't necessary for landing. Jim