There are quite a few software programs for handling Questions and Answers, and help desks in general.  Many of them are free.  Dr. Reza Asaday reza_asady@yahoo.com can provide advise as to what might be the optimal software.

In general the type of platform is not that important. One can be up and running with many of the platforms in less than an hour.  All of the materials in the Library of Alexandria help desk are free where and they can be included into any  other platforms.