I was looking at those suggested questions -- they look too much like a survey. This population isn't a random sample of anything, so you aren't doing a survey. It seems that what you are really interested in is whether or not any signatories were misled into signing.
E.g., no one cares if the DI 400 believe in God or not -- what matters is whether or not the signatories who signed up to the DI 400 list were made aware that their name was going to be used as anti-evolution, pro-ID propaganda. While I'm sure many of the signatories do support that usage (many are straight-up creationists), there is a good chance that many others are, for example, theistic evolutionists who think that evolution is good science, but that oppose those who campaign for atheism under the flag of evolution. They may naively assume that the Discovery Institute is an ASA-type association for religious scientists. Many theistic evolutionists hear "intelligent design" and think of the idea that God is guiding the universe, which is not in opposition to science (although a matter of theology, not science). They don't realize that the real goal of ID is bringing divine intervention -- special creation of organisms and/or DNA -- back into science.
Others may simply have taken the statement at face value (which almost any scientist could agree with, taken at face value -- even Richard Dawkins!), with no knowledge of the ulterior motives behind it, and the uses to which it would be put.
You may find it surprising that anyone could be naive about these things, but there is still a large segment of the population that is not web-addicted, that does not google everything that they come across. Particularly this applies to older folks. I think the guy who dropped out of the DI 400 was a professor emeritus.
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