Bob
I think it is a great idea. I propose an instruction section or FAQ on using the forums features (including chat) as part of the effort.
As for actual garden railroad info let Sgt Joe Friday set the tone, “Just the facts please”… Stick to explanations not recommendations on specific manufacturers, operating systems or other details. Leave out the examples and the “here is how I did it”…that stuff is why there is a forum.
Lock the threads on each subject and let all of us send you our submissions. Or have a discussion thread that is open to all from which the basic info can be culled for posting in the locked area. I know you are a busy important Dictator benevolently ruling his empire from high in the black tower of oppression, so while this would be more work for you up front, once it is done there would be very little maintenance needed. It would also keep the thread drift, brand loyalty fights and opinion prophets at bay.
Once you go to all this trouble you certainly want people to find it easily so a button or banner (clearly labeled) on the home page and hot linked to the section might be worth the effort.
Here are a few subjects I think that should be included because they are routinely asked:
Track - code, materials used (and their attributes), connector types, tie types, cross section measurements
All things curved - Radius / diameter (yep some peeps like me were stuck in the second grade all those years and never learned this) angle / divergence for turnouts, minimum operating radius
Power types - DC / DCC / RC Batt / Wind up rubber band
Scale vs gauge - selective compression, toy train, Fine scale, Manufacturers by scale (not who is best though cause we all know the answer to that one)
BBQ recipes (the official GR food) and techniques - Hot / cold smoking, hardwood / broasting, wood choice / oak / hickory / mesquite, horizontal / vertical smokers
This what you get for asking. My $.02 and as always dumb ideas are still free.