2. How many of these people hold staunch views on the questions asked? E.g. would this have the same effect on a extremist skinhead as it would on the average college student?
Probably most of them. This mechanism has been described by Cialdini as "Commitment and Consistency". Marketers abuse this in a clever way by ramping up commitment. If you answer a bunch of seemingly innocent questions to make you look good ("I often go see opera"), you have made a small commitment. Then it can be leveraged to sell you an expensive opera discount card ("For a person who visits opera so often, it would be irrational to turn the offer down".)