Most sport models I've dealt with actually have right thrust, hence they aren't 0-0 on thrust, but that's a minor point.

Incidence was well described, i.e. it is the relative angles of the engine, wings and stab. I'd like to try to expand on it's importance.

Planes are a balancing act between many forces. These forces change as conditions such as thrust, airspeed, altitude, etc. change. The designer of a plane will attempt to set the engine thrust, wing incidence, stab incidence and CG such that the plane will fly at a constant altitude at a given airspeed and thrust setting at zero trim, typically this would be your cruise speed and is not necessarily wide open throttle. If you think about how planes fly, the effect of thrust, and why most planes have stabs, it should be obvious that the angles between these components is critical. Their relation to CG may be a bit more difficult to grasp, but take the easy one, the stab. If your CG is rearward, the stab will need positive incidence to hold up the heavy tail. Move the CG forward, the incidence on the stab needs to be lowered, etc. Beyond "level flight", the incidence of these components (and CG) can have a large effect on aerobatic models. Issues such as knife edge tracking, upline/downlines, etc. all relate to incidence. Small changes in incidence can have large effects in how the plane flys. By small, on precision aerobatic models one can easily see the effect of 1/8 degree or less change in incidence. While sport planes and the average sport pilot are probably less sensitive, it should go without saying that incidence, thrust, CG location are very important and you should take care to ensure they are set "properly" on your plane.

"Properly" - this is subjective. There is a wide range of combinations that will work for a given plane, but the plane will act differently. CG is the obvious one as it is common knowledge that you can move this around some, but wing, stab and engine incidence can also be "adjusted." While typically a bit more difficult to fiddle with (unless you have wing/stab adjustors), plane performance can be greatly enhance, or diminished, by changing the incidence of the wing, stab, engine.

To get a feel of how this all works, download an advanced trimming chart that offers solutions that include incidence changes. There is one at the NSRCA web site --> http://www.nsrca.org/trimA.htm