Oh my god please leave those small businesses alone. That webshop is probably just a handful of people and they have no clue what their legal obligations concer

Oh my god please leave those small businesses alone. That webshop is probably just a handful of people and they have no clue what their legal obligations concerning GDPR are. They would probably need to hire an expensive lawyer just to find out what information they can and should share with you if you start making trouble. At the same time you expect all this information for free. If you want answers to your questions, my recommendation is to ask more specific questions. For example, you might ask them if they share your data with a credit reporting agency, or if they send email newsletters, etc. That way it'll be much easier for them to answer, and it's more likely you'll get useful results.