All of the project level summary information like Start/Finish dates, total duration and so on is stored in a task with TASK_ID == 0
.
Task Note or Project note in your case is stored in MSP_TASKS.TASK_RTF_NOTES
column. Here is a good article how to read the field and use it in reports: http://blogs.msdn.com/b/chrisfie/archive/2008/06/04/how-to-display-microsoft-project-task-s-notes-field-in-a-report.aspx.