Deep Q on Moon's Orbital "Habits"

Factual Questions
1

Recently, I stumbled upon the fact that the nodes of the moon’s orbit (i.e.: the two points where its orbit crosses the ecliptic) exhibit precession. I believe it is called “the precession of the lunar nodes”. (It is a cyclical phenomenon with a very long period from one cycle to the next.) But, I fail to understand why the lunar nodes should exhibit such behavior? Doesn’t the moon trace the same orbit ad infintum? Obviously, this is not the case, but why not? (A WAG: Is it because the earth-moon system orbit about a common center of gravity rather than the smaller body truly orbiting dead-center around the larger?)

Perhaps some SDoper has a better handle on what is happening here.

2

The phenomenon is usually referred to as the “regression of the nodes”. It’s similar to the Earth’s “precession of the equinoxes”, although, as the name implies, the nodes move in the opposite direction.

Rather than having a “very long period”, however, the nodes complete a cycle of regression every 19 years, which is rather brief by astronomical standards. (Compare to the Earth’s 25,800-year cycle of precession.) Regression occurs because of the tug of the Sun on the Earth-Moon system.