1. I think you are required to answer it. As in they can fine you if you don't. Their response rates are something like 95 percent.
2. My Dad's business was in their panel (which means it was repeated year after year) and he had to report pretty confidential financial data, but he did so.
3. I am very familiar with how confidentially kept the data is, and based on my knowledge I'd be happy to to answer their questions accurately. They anonymize their data to the 1 in 100,000 level, in other words if anyone could guess it's you based on your location, other personal data, etc. then the bits of data that would identify you are removed. It's a major hassle to researchers like me.
4. I am hoping to get access to the confidential "microdata" for one of their (Census) surveys soon. It is a huge hassle, needs approval up and down the line, it's expensive, you have to be a US citizen to get access so our mostly foreign grad students can't go there, and when you get access it is in a clean room, with only their computers which are not networked. You aren't allowed any electronic devices in the clean room, no cell phones, no email all day, nothing. And they have one-on-one supervision for researchers using their confidential microdata and they log every single keystroke you make on their clean-room computers.
5. I have been using their non-confidential microdata a lot this year, in fact I am working on some tonight.
In summary, help a brotha out and answer the damn survey accurately. And fuck Obama.