You can certainly tell them about the sheva mitzvot. While not everyone agrees the Rema (Teshuva 10) says that they must adopt all of Choshen Mishpat so you can tell them about the laws of neighbors, torts, etc.
I would think several times before telling them about the CR as the multiplicity of opinions might confuse them (unless they have legal minds) and the lack of civility might turn them off.