Hi Scapes,
Welcome to Auctiva! You are correct that the links promoting Auctiva's services are added at the time the listings are posted. We do not offer an option to exclude those links from your listings so the only way to remove them would be to revise your listings after posting them to eBay to remove the links as you mentioned you were able to do.
The shipping calculators for both eBay.com and eBay.com.au are supposed to provide exact shipping estimates based on the shipping services being offered and the attributes of the package that you enter. I’m not sure why the eBay.com.au shipping calculator would produce high estimates so you might want to touch base with eBay’s customer support group about that.
If you have any other questions regarding your account, please feel free to contact our customer support team using the form on the following page of our site: http://www.auctiva.com/help/requesthelp.aspx
-Mike