Hi I need to know if the below scenario is possible as everything i have read so far says no.

I have a case with a email linked to it. The email also has attachments that are linked to it. What I would like to do is export all the related information out of Salesforce.

Is this possible?

Master: Project 
Child: Time Sheet Line Item 
Time Sheet Line Item formula field Total Line Amount (Total_Line_Hours__c * Project_Task_Billing_Rate__c) 

I am trying to create a Roll Up Summary field on Project to SUM Total Line Amount field on Time Sheet Line Item, but Total Line Amount is not available in the drop-down (other formula field Total Line Hours is available). What am I doing wrong here?