You need to enter than information into your theme's template files, wherever you want dripped product info to show up. You don't have to enter that information for every single product/post.
You need to use the script so that you can insert your affiliate ID into the affiliate links. Otherwise, you will find yourself editing hundreds of custom fields.
Basically, you just need to make a couple of changes here and there... you certainly don't need to edit hundreds or thousands of posts.