Link to prefill form submissions. 
http://domainname.com/ACA-Fest?entry=5da0b1e8-8332-49a6-b76f-94b74caab84f
The GUID that you put in the link can be found in the action form reports table, avtActionForm_Reports.
Here is the token to insert in an email to get a link  back to the form with the content inserted:
[_EditUrl]
Here is a sample SQL query to get that data for a submission
SELECT 'ReportEntryId: ' +
      CONVERT(nvarchar(10),ReportEntryId) + ' UserID: ' + 
      CONVERT(nvarchar(10),UserId) + ' submitted on: ' + 
      CONVERT(nvarchar(11),DateSubmitted, 102) + '|' + 
      CONVERT(char(36),ValidationKey)
  FROM db_Name.dbo.avtActionForm_Reports
  WHERE ModuleID = 1037
   ORDER BY ReportEntryId desc
This query could be improved by including some data from the form submission, like a name of the person submitting the form. That data is stored in the record in an xml format.