How this works in Preference is that you create a category named “Portfolio” and each portfolio item is actually a post. The only real difference is that there is a setting to display the portfolio items (posts) in columns of 1, 2, 3, or 4. You can however, have sub categories in the parent category of “Portfolio” which you can then create a custom menu and assign it to the portfolio menu location. This also means if you want a portfolio category named “Book Reviews”, you can do that, but it has to be a sub category.
One note about the portfolio layout…it’s a little finicky with the layout when you start getting more than one row of items (posts) and can go a little offset from each other. If you go the route of the portfolio method, make sure any Featured Images you use for each are the same size.
For the image being linked…unfortunately it links only to the full post item view only because it’s actually a “Featured Image”. You can however, add a button into your content and link it to your Amazon.
One more note…because I plan on rebuilding Preference from the ground up (a nice fresh new Preference), I will be changing the portfolio to be a plugin so that if you change themes, you won’t lose your portfolio, and it will also have a better layout structure.