Oh, ok, this is already supported, except for the link target.
To add additional link types requires to be added by code. It is fairly simple. Here are instructions on how to add custom links that I gave to another user.
After you add your custom link types, you can import and export to them. Make sure you have the latest version of the CSV Import installed. You have the option to make a CSV field for a link title field. If you are importing modified CSV files from the built in CSV export these fields will automatically be mapped for you.
Hope this helps!