ORIGINAL: MinnFlyer

Breath, yes. Opposite, no. If you are banking left, you would apply left rudder.

You bank the wings with the aileron (Let's say 30 degrees). Now the lift you are generating is still the same, but you are generating it 30 degrees off from the direction that gravity is pulling you, so in a sense, you are generating less lift. This will cause the plane to drop so (as you know) you hold the nose level with elevator.

While this is all happening, to must remember that the outside wing is moving faster than the inside wing, so it is generating more drag. This sometimes causes the outside wing to lag behind a little and it is what is known as "Adverse Yaw". It is much more pronounced on slow planes with big wings (Like a full-wing Cub)

The best way to imagine this is to picture yourself sitting in the center of the cockpit with a stick poking up a few inches in front of the windshield and a string tied to the end of the stick. When you are flying straight, the string is being blown straight back. When you go into a turn, you want the string to continue blowing straight back. But if you are getting adverse yaw, (and you are in a left turn) the string will start to point to your right shoulder (Because the right wing, which needs to move faster, is lagging behind and causing you to yaw to the right while you are turning left)

So to keep that string pointing straight back, you need to apply some left rudder to counteract the yaw.

How much? No one can answer that. It's like saying, "How much do you turn the steering wheel of a car to make a turn?"

But usually, only a tiny bit of rudder is needed (If any at all - most of our small models don't suffer from enough adverse yaw for it to be a concern)