There is such a place already: meta.
On meta moderators and other users can request support, start a discussion or do a feature request. Moderators can pin such questions on the featured section so those posts are visible on the main site.
The spam protection mechanism is there already too: you need 5 reputation to ask a question on meta.
For private communication between moderators and users there is a distinct system in place that users can reach through the Contact us page in the footer.
Moderators can also change some sections in the help center to explain some site-specific rules.
For private communication between users, there is no place, and shouldn't be. Stack Exchange is not a social network and it will never be.