Hello Markus Berchtold,
Your assumptions in question 1 are correct. Since you will be using a web application you will have to build the project and code files before publishing them to the live environment. If this approach appears too clumsy for you, you can take an alternative approach. Following the instructions from this KB artilce
you can create your own VB Sitefinity website. In short what you have to do is to open Visual Studio and create a new website, not web application project. Then take all files (excluding SitefinityWebApp.csproj file) from the _EmptyProject directory which gets created from the Sitefinity 4.0 Project manager. Amd add them to your newly created website. Then you will be able to work in the same way you are used to with Sitefinity 3.x.
The drawback of this approach is that you will not be able to manage the created websites from the Sitefinity 4.0 Project manager and you will have to manually upgrade them.
Our developer's guide
contains examples on working with the Fluent API in all areas of Sitefinity. You can browse to the Pages section for example and see Native and Fluent API samples side by side.
All the best,
the Telerik team