software suggestions please

[turbocivic16]

In the process of developing my website. Basically its a site specifically for my college in which I plan on getting local businesses to advertise on.

I need solutions that will allow these sorts of actions on my site;

a anonymous posting system that is not a forum. I want users to be able to get online and just post a limited amount of characters to a boxed in area on the homepage. This may be further evolved to something where they must register to do so...not really sure yet. This could be used for like users getting online an posting breaking campus stories like; "fire in chem-phys building" or "John wall signing autographs at the student center" or "Campus parking sucks"

I need a marketplace system in which users can post things they are selling and have an ad show up in the designated space.

I also need a system where I can post a gallery of pictures and have users be able to comment on them.

I would also like everything to be facebook/twitter intergrated so anything new can be posted to FB.

Any suggestions?