Sites like this run on Content Management Systems. You can find a good comparison (including demonstration admin logins) at opensourcecms.com.
Personally I recommend GeekLog
, as it's secure, fast and very cutting-edge. The default template looks a bit out of date, but some of the features (Remote Authentication
immediately springs to mind) are very advanced.
As for hosting, I'm sure you already have a bunch of recommendations, but I've just added one to the end of this post
concerning my own hosting company (affordable and good for starting off, more advanced users may want to look elsewhere).