Ask HN: What questions should I ask for custom CRM development?

I have a potential client who would like to build a custom CRM solution for their large (+$500mm rev/yr) company. I am putting together a questionnaire for their employees to respond to in order to best determine the problems they face with their current system and the features they would like to see in a new custom system. What questions should I ask to elicit the best, most informative, and actionable responses from the employees?