Hello Dylan,
Because of Newton's laws of motion we have that whole action and opposite action thing going on, or commonly in our world prop rotation in one direction and toque roll in the opposite direction. The larger the mass and resistance in the prop the more counter-torque is generated back to the aircraft.
For multirotors this is a big deal because so much of the flight is focused on the motors where as with fixed wing aircraft the structure is also a huge factor. Quad's use torque to turn about the vertical axis (yawing). It is not necessary for a multiple prop fixed wing aircraft to have props spinning in opposite directions.
When you say iyour FT Cruiser spun, about which axis did it spin? Was it a spinning yaw or a spinning roll? A spinning yaw sounds most likely and if so could be because one prop was delivering more forward power than the other. If it did yaw, was it to the left or to the right? If one of the motors was reversed when it shouldn't have been then it would certainly yaw very strongly.
Regarding your ailerons, another Y cable would be my choice though I believe (I haven't done it) you can accomplish the same using an aux port on the receiver.
This sounds like a very fixable problem to don't lose heart.
—Jim
