Legal repercussions

The information you found is right. It's pretty amazing that somebody who can legally enter the country anyway would be committing a "crime" by thinking seriously about getting married, but that is the current law. And the penalty is a 10 year exile.

The best advice I can give to somebody just starting the process is to talk to an immigration lawyer, tell them everything they ask you about, and take the process very seriously. You can get an initial consulation with an immigration lawyer near you for $100:

http://www.aila.org/content/default.aspx?bc=12621|10180

Even if you do everything right, you might still face some real problems with the immigration system, even as an American citizen. My wife couldn't see her family for 4 years because the governement did not process her case. Only a law suit got them to act.

In general though, what is really needed is some changes in the law. In some cases, this is the only option. As a result of my own experience, I helped start a group called American Families United with other people who are or were separated from their families. We got together and hired a lobbyist to work on our behalf, and we have some interest in improving the system. Members of our group also are working on documentaries, and many of us have been in newspapers or on TV. Please keep us in mind as you go through the process or if you'd like to help make things better:

http://www.americanfamiliesunited.com