The welcome message I feel should be too priority on new implementations to the forum, and the way I see it, would not need much tweaking of the current system, just a pop up for brand-new members.
A welcome message would really be helpful and directing them towards some threads explaining the forum rules and little bit of forum functionality tutorial will also be helpful but that would go into too much demands seeing that we are not seeing simple updations also but if implemented can help newbies a lot if they intend to learn it.
Possibly, that could be some solution to some of the repeated question threads on the forum although, some users might play ignorant or not to have given it much attention but it could help for genuine newbies and for some other newbies that gives attention to what is presented before them.
Some things on the forum like hidden mail address arealready some addressed privacy concerns by default, repeated merit, activity and se forum functions that continues to get a repeated answer could be explained by a default welcome note or possibly with links to where newbies would get clarification other than having them start there own episode.