It's a bit of a mess right now, and needs cleaning up. A lot of the actions could probably be moved to their own functions that can be used more than once, and many should probably be moved to their own .php file for readability's sake (this will require modifying the .htaccess and making a new interface folder).
Specific requests:
Add return_to functionality to every form, and simply reset user to homepage if return_to is not specified. This will remove a lot of the work of finding and specifying the $rpage on each action.
It's a bit of a mess right now, and needs cleaning up. A lot of the actions could probably be moved to their own functions that can be used more than once, and many should probably be moved to their own .php file for readability's sake (this will require modifying the .htaccess and making a new interface folder).
Specific requests: