The difference between the 314.2 and the 295 comes about because the measured line is offset 30 cm from the curb. Thus the circular course (measured at the center of a 10 m wide roadway) will have a diameter (5-.3)x2=9.4 or a circumference 9.4xpi=29.5 meters. Or, for 10 laps, 295 meters. No conflict here.
Tom Knight first proposed using the idea of "degrees of curvature" when describing a course. Add up all the right and left turns in a course, and the result is the degrees of curvature, a good index of twistiness.