I think you can use PegaKM(Knowledge Management) to create an article which contains FAQ.If you have the license for Customer Service (CS) then it is enough no need of separate license for PegaKM. Pega KM will be automatically installed when you install CustomerService . You can use Pega KM alone as well that is without CS framework.
Using Pega Survey you can create a survey and send it to the users to find their response. PegaSurvey is integrated with Pega Platform (PegaRules). I don't think any additional license is needed for survey.