My balance isn’t as good as it used to be, so hopefully I won’t fall of my tree stump before I finish this post…
First off, stop using the term ‘newbie’.
I agree with Jon that having new members fill out a questionnaire about experience level and such would be a bad way to start. There are folks who have been on here for quite some time who haven’t even filled out their own profile (I’m looking at you rubmybelly!).
Perhaps you could just start a thread each month, and make it a sticky for a couple of weeks, inviting new members to say hello and such. Don’t use the same thread every month, start a new thread each month, so it won’t get too long or bogged down. You could put these threads in their own forum, new member forum as you already suggested.
I don’t find the idea of mentors and such as necessary. I’d go as far as to say it seems to me a bit silly. Backpacking really isn’t some hard skill, regardless of how much the engineers want to try and make it so (sorry David T… :-). The folks that are always helpful, a small but vibrant group on BPL, will naturally gravitate to any new member forum to see if they can be helpful. Perhaps you could give those people a different designation (but not mentor! :-) than ‘BPL member’.
As always, first impressions are everything. BPL hasn’t always given very good first impressions (I still remember the poor REI guy who got hammered for offering to help people here), you might have to pay a bit more attention to a new member forum to ensure the cantankerous don’t hold sway.