There is no official limit on the number of questions, but we recommend a max of 5 to avoid causing survey fatigue (2-3 is the ideal amount). The more questions there are, the less likely students are to complete them, particularly if there are instructor or open text questions.
For the most part, questions are accepted as is. If there is a situation where we feel that a question could be phrased better, we’ll offer suggestions (our survey team has a lot of experience in question design), but ultimately it’s up to the department if they want to accept the suggested edits.
The only times we would reject a custom question is if it is asking for personal information that might circumvent student anonymity (such as race, gender, etc.) or if it duplicates a question from the core question set.