These variations in revolution and rotation are indeed quite complex and wonderful. Superimposed on the first order circular motion of precession is a second-order sinusoidal wobble called nutation, caused by periodic variations in the lunar orbit. No doubt there are also higher order perturbations. There is also a very slight long-term variation of the obliquity of the ecliptic (that 23.5 degree lean of the earth relative to the ecliptic) which is kept within narrow limits by the moon, but which is nevertheless suspected to have profound climatological consequences. The fact that Mars has no large satellite and its obliquity varies enormously is one reason why it's suspected its climate is so different. It also gave rise to the concept that large moons are essential to moderate climate changes (bad news for SETI enthusiasts, if true). The precession of the earth's orbit, (the technical term is rotation of the line of apsides) may also have climatological consequences.

The entire solar system is a chaotic system (by this I mean Chaos theory-determined, not random and confused) that has achieved a complex dynamic equilibrium of resonances. It is amazing how Newton's simple little laws give rise to such rich and varied phenomena.

It is fortunate that all of these effects occur on such enormous time scales, giving life an opportunity to evolve and adapt to them.