I've updated the original post to include a link to the design concept's project files. Devs out there can deploy it to a WP8.1 device to get a feel for it if they want to.
I'm a WP8 developer and I would like to join in to help as much as I can with other developers if they are willing to work as a team to develop this app. API access can be an issue but I guess it can be made possible just like how Instance or 6tag was done. Need advice and support please.
I'd be more than willing to team up with a few devs to bring our community the proper app experience it deserves. Facebook's public api to get and post content to Facebook seems sufficient to create a full-fledge app but my main concern is the push notification situation. As far as I know, there's no way to implement real-time push notifications from Facebook's service to third party apps. The original Facebook app from Microsoft during the WP7.x days had this problem and relied on Microsoft's servers to periodically check for notifications and thus causing a delay. This is the same situation with 6tag, 6snap, etc.
Now with the current FB app, Microsoft and FB is jointly working on this app so the app have direct access in order to enable proper push notification. I feel that no matter how wonderful this app looks and performs, it'll always be playing catch up in terms of maintaining api use and lack of real-time notifications.