That's an excellent question and honestly I'm not sure how to address that. I'll let the community chime in how we should guide the users appropriately to a Q&A platform Vs. Forums (Discussions) platform.
I do have the answer to your other question. There is native integration between Live Forums and Live Exchange and you could easily move a question from one module to another.
All of our community engagement modules (Helpdesk, Knowledgebase, Forums, and Exchange) are integrated with each other so you could take a ticket and create a knowledgebase out of it. Similarly, you can take a discussion or question and convert it into a ticket on Live Helpdesk.