I have also a community web site (http://www.vihegay.com and http://www.intergayhiv.com), so i can suggest plugins which work very well !
Use s2Member plugin for let people see your pages based on their membership level : http://wordpress.org/extend/plugins/s2member/. In my web site, if you are just a visitor, you do not have an access to the comunity, you must be "Membre Coucou" (you can have your own membership label) at least.
Use the Widget Logic plugin for let the specific widgets to appear on the pages needed : http://wordpress.org/extend/plugins/widget-logic/
When you activate the widget, you go to the widgets page, you open them and at the bottom of them you find an empty space where you must declare on which page you want them to appear. For example, to have a widget only on the home page and contact page, you type : is_page(array("home","contact"))
let me know if you have a problem !