Can we search and install community addons for v7.0 via the Apps menu? Is there something special to do or is it broken?
Not yet, but OpenERP v7 already integrates the whole technology to make it work. We just to activate it on apps.openerp.com but we are waiting to have more modules ported to v7 and to fully test this feature with real community modules before activating it.
Apps seem to be just for certified openERP modules. You can add non-certified community modules to your server addons path, goto settings > installed modules, delete the "installed" search filter and then all the modules available on your server will display.