As ProThoughts mentioned, the appropriate way to get the URL should be using the Q2A functions themselves. E.G.: calling the qa_q_request() or qa_q_path() functions for each question. However, if this is not possible you can still get around this.
The URL for your questions is basically the protocol/schema, the domain under Q2A is being stored, followed by the root to Q2A and then the question ID. The title is not really necessary (it is just there for SEO). Considering you want to access the URL from outside the framework, you will need absolute URLs rather than relative. That actually simplifies things as you just need to go to admin/general and get the value from "Preferred site URL" to get everything but the question ID (e.g.: http://www.question2answer.org/qa/). Then, it is just a matter of appending the question ids.
So the full query that returns question URLs and titles should look like this:
WHERE title = 'site_url'
WHERE `type` = 'Q'