RE: Aileron Trim
Try a straight ahead stall, the higher the nose angle the better. If the airplane falls left (for instance), the left wing most likely has a higher angle of attack. You can gently twist the tip l.e. down and heat monocote with a gun to fix.
Next, point the aircraft straight up in flight and reduce power to idle. If the nose falls CONSISTENTLY left (or right) the rudder is misaligned.
To find if the thrust angle is correct, measure prop tips to fuse tail with the prop horizontal. You can also see thrust alignment problems if an application of power turns the plane after being trimmed.