Short answer: you can't.
The list of columns that you can export is fixed, and you can only adjust filters. If you need to blend or join data in some way, you need an external app with these capabilities.
If you need to export orders for some kind of reporting, look at reporting apps (you can select what data to display and export) such as Advanced Reports.
If you need to export orders for other purposes (e.g., importing to other systems) or for automation, look at Mipler Data Flow, which can also export and blend data.
