RE: rolling circles?
I used to do rolling circles as Jaka described, using only aileron and elevator. As my skills progressed, I learned to coordinate the proper rudder inputs. Now, I can do rolling circles with only one roll throughout the 360 turn, as well as any number of rolls or even point rolls! With 3D planes, I can do them in a diameter of about 2 fuselage lengths, or make them as big as I desire.
The first thing you need to master is the slow roll. You should be able to do a 4 second slow roll, without the airplane changing direction or altitude. Once you can do that, You are ready to start rolling turns. You will vary the elevator and rudder inputs to control the diameter of the circle and maintain altitude.
I like to start mine flying from left to right at about 1/2 throttle. Just as the plane is in front of me, I start the maneuver with with left rudder input, then right aileron (hold constant aileron), then down elevator and more left rudder as the plane passes through knife edge, followed by right rudder and down elevator as it comes to inverted. Transition to to left rudder and up elevator and more left rudder as it passes through knife edge and reduce elevator and back to right rudder as the plane comes back to upright .. Repeat all the way through the turn. I started making 90 degree rolling turns, then practiced 180's and finally the 360's.
At any point where the plane is banked, you are actually inputting both rudder and elevator. Depending on the plane, You may need to vary the amount of aileron to keep the roll rate constant too! A proper rolling circle is really beautiful. But, they are very difficult to master. It just takes practice, practice, practice!
Good luck!
Doug