Wordpress has a "posts" facility. Not sure how it works, I think participants have to register. There would be hundreds of free add-ons that would address a lot of the features you require. A bit techy but the whole point about Wordpress is that a lot of the real techy is dealt with up front. And it comes free from a lot of providers.

Stroud Folk Weekend is configured for people to get e-mail notifications of anything posted - which as far as I can see - the posts are instigated by admin personnel. Like me! But I didn't set up the system, I took it over because I have a Wordpress site eleswhere - Stroud Voices (.co.uk) ( post/bulletin board not configured)

I have had experience of Drupal websites and am glad I don't experience it now. Definitely techy.