Item price plus delivery charge is not free postage.
If you are a pro-seller with a newer style account and list in any other category you set your shipping rates by going to Settings > Shipping Settings. To set free delivery change figures to 0.00.
Then manually change your item prices, if you wish, or use the Price and Quantity template file to bulk change them.
How do I access the "Price and Quantity template file" - Seems exactly what i'm looking for.
Right click over the file name to save the file. Once you've filled in all your stuff save it as a text tab delimited file.
Upload via Inventory > Add Products Via Upload. Choose "Price and Quantity file" as the file type.