[support] Using a DS layout in Panels

I have a hole in my knowledge of Panels that needs filling :) I created a DS panel for the node display for Commerce product-display. Works fine.

Then the requirement changed a bit, so I decided that the product/xxx URL will be controlled by Panels, using a 2-column panel, and that the left side will be the DS layout.

There is a DS choice in Panels when adding content, but it is not for selecting a DS layout.

I don't see a place in Panels where I can add a content type (ie product-display) as content.

So, two things driving me crazy. How do I get Panels to use the DS layout for the content type. And how do I use the product name as the context (Panels only lists product id, which is a number, which should not be the URL)?

Thanks!