Not amateurish at all, but good questions. I’m not confident enough to answer your second question, but on your first question: yes, you can use the hosting service you already have. Given that you are renting a VPS that is. It looks like Strato is calling this “hosting”. Don’t use their “WordPress hosting” package for this though, as it won’t allow you to install the instance software.
On the outside it’s sold as security, but what you really get is surveillance