These surveys are notorious for asking a lot of questions beforehand, but this is only because they are trying to learn about you. They may ask questions about your household and income, but this is only because they want to match you to surveys that suit you best.
It is recommended that you apply for several sites at once because there may only be a few surveys available for you on one site. This is also a good idea since surveys will stop being offered if they reach of certain amount of people taking the survey. The work may become repetitive, answering questions, but the payout can be quite nice if you are willing to stick to it.