[snark]

Ok. I found the General BP setting to “Disable activity stream commenting on blog and forum posts?”, which I set to “disable”. I think this is a good solution — users can reply to Group or Activity posts, which are synced in both places, but now if they want to reply to a Forum post that they are reading in the Activity stream, they have to click through to the Forum post and reply there. This will keep the site from generating two sets of conversations.

As to my point #3, I’m still hoping for a site-wide “Favorites” option, but especially for Forum topics and replies. This is why I have filed a trac ticket for it, which others seem to agree is an issue to be fixed.

Thanks for the tip!