BuddyPress.org

1. Have you tried BuddyPress Group Forums & bbPress (or known as Sitewide forums). Both of them integrate well with BuddyPress and will show up in the activity stream when someone start a topic or post a reply.
https://codex.buddypress.org/getting-started/installing-group-and-sitewide-forums/

2. I think most of the BuddyPress compatible theme should fits your need. You just need to configure it so it looks like a normal blogs in the front while still maintain the social media functions.