The way I see it, question #1 is the only one the Constitution authorizes them to ask.

I guess you all have probably seen the census web site. They talk about "protection of information," then say it's illegal to misuse the information. Duh, we know it's illegal, but that doesn't mean it's well protected. Just like the dude says on the video, it's probably not wise to give them any information you wouldn't give to a stranger.