If there are many questions, put the most important ones on the first page, and make everything else optional.
Any question that requires more than 2 seconds to answer should be optional. (That obviously includes any question that requires clicking on a link to an external web page with a long explanation of some definition.)
Given that it's been a while since the last survey (http://lesswrong.com/lw/lhg/2014_survey_results/)
It's now time to open the floor to suggestions of improvements to the last survey. If you have a question you think should be on the survey (perhaps with reasons why, predictions as to the result, or other useful commentary about a survey question)
Alternatively questions that should not be included in the next survey, with similar reasons as to why...
survey is now up (2016-03-26) http://lesswrong.com/lw/nfk/lesswrong_2016_survey/