Given that the type of user asking the questions is a new user, no, I can't imagine most of them bothering to go back to edit their post once their question is answered.

To edit other people's posts would need a forum moderator, or a volunteer who could edit one particular post that they created (e.g. your post at the top of the thread could contain the questions and answered copied and pasted in - not that I expect you will have time for this!) or a similar wiki page that could be edited by anyone with the questions and answers. The problem after a while is that the lists of Q&As will get longer and longer, and will need to be categorised (hardware, OS, multimedia etc.) to be easy to navigate.