InfoPath Dev

I have set up a form where I am using the @ID for the sequential form number BUT I am concerned about duplication.  Is there a way to concat filename with @id .. please provide the actual formula to put in the Expression Box?  

I must have been working on this form entirely too long because I don't understand how to set up the rule in the drop-down.  I have created a form with a drop-down field (Person's Name) in the primary data shource  - how do I have the system pull in and display (expression box) with the matching information (telephine and email) ...