I think ETP should mount its own folder for each site node. This should be unique to ETP, so that it does not interfere with any package folders. I am not quite sure how this can work with the existing content repostiory folders. Perhaps ETP would maintain a parallel cr_folder tree, so that we have an ETP root folder, and all the ETP managed folders live under that, so they do not clash with other content folers.
I agree, Forums needs to break out into one forum per package instance. But we need to acknowledge the issues that raises such as moving messages betweek forums instances, similar to the problem we still have moving bugs between bugtrackers. It is just a UI problem, but we need to keep it in mind.