The answer to this question depends on who your audiences are and what they need to know. In this case, a survey of students just entering the major is appropriate. Surveying graduating seniors would give you this information. A General Studies evaluation may be concerned with only those students entering or exiting the particular course or courses being evaluated. Accrediting agencies sometimes require information about department alumni.
Some departments designate a committee or even one faculty member to design a survey.
A good place to start is by looking at surveys that have been done in departments similar to yours. A survey should only take about 15 minutes or so to complete. Appearance is, of course, important and the survey should be easy to fill out, with clear and concise instructions. A cover letter that explains the purpose of the survey and assures the confidentiality of the respondents' answers can make a significant difference in whether a survey is completed and returned. Whether or not you ask students to put their names on surveys depends in part on whether the surveys are to be mailed or given in class.