There are rules, and then there are rules.
Yes, we have the Ten Commandments and the Six Precepts of the Church to follow. But the Church also has a code to follow.
The Code of Canon Law.
While these regulations have developed over the history of the Church, they were first codified in 1917 and then amended in 1983.
To see "the tip of the iceberg," let me introduce you to Dr. Edward Peters. He provides us with two great sources of information. One is his 'blog on how Canon Law can (and perhaps sometime should?) be applied, giving his opinion on topics that ocassional arise. (Please check out the archives regarding the Terri Schiavo ordeal and the "communion for pro-choice Catholic" debate.) The other is his own personal webpage, a resource into how to apply this in one's life.
In Light of The Law is the name of his 'blog. CanonLaw.info is his webpage.