Hi Catherine.
The promoted proerties can be used in the catalog or "Qform" templates.
Not sure if you have seen this but you have some sample forms. One form can view all of the assigned forms in the database, often as an alternative to the web part.
So instead of this process.
Go to Sharepoint in IE.
Browse to the libray or webpart.
Search or scroll for the particular document you want.
Select it.
Wait for InfoPath to load and display the form.
Then close the form and repeat.
If you have a lot of forms you are working, this is not a very efficient process.
Instead you can open a catalog form in InfoPath once and it will show you a filterable, groupable, searchable, list of all of the documents and you can move in and out of them without leaving InfoPath.
This is one way to really leverage Database Accelerator, but it depends on your workflow, and requirements.
I have not really used the webparts but I do not think they use promoted property functionality.