Is it possible to customise the mini shopping cart, for example shipping information, cross-sale products etc.?
It is not possible to customize.
Also it is good to note that it is not compatible with mobile so it will not show up at all on a mobile browser. Wix will direct users directly to Cart page once an item gets added to cart via a mobile browser.
doesn’t that work by code? or could you programme your own shopping basket?
The mini shopping cart is not codable.
You can create your own shopping cart look-a-like by using a lightbox. Then you can code the rest of the checkout function.