You would export as a CSV. Depending on what you are doing, you can select Export All Data, which will allow you to get the database_ids, name, etc. If you are import-exporting then you shoud use the import export to update the tables. But I needed to import 2000 Quotattion with 27000 lines, so I created the sales order csv with a combination of both. The key is to understanding the structure of the tabels. I use pgadminIII to view the tabels to understand what I am looking to export. I am moving 100,000 records from asystem that is 20 years old and mapping data in both directions. It works, but spend time testing to make sure you validate your csv on import.

I also would use LibreOffice since it will import the csv correctly. If you want to use excel, you should use the data import from text file, not open the csv directly, Excel will drop leading zeros without warning.

Have you tried CSV?  Excel can open CSV files.