When using the extension to create an installer for .Net 6/7 you should add "Publish Items" to the installer project instead of "Primary output".
Also, the Q&A for the extension at https://marketplace.visualstudio.com/items?itemName=VisualStudioClient.MicrosoftVisualStudio2022InstallerProjects&ssr=false#qna includes the following answer from Microsoft to a question about dependency detection -- "Due to the different way dependencies are detected for .NET 6.0 projects you generally won't be able to rely on what show's up under detected dependencies. You'll have to see what gets added at build time."
I'm not sure what you mean. I suggest you ask a new question and provide relevant detail. For example, are you asking about an icon for the installer (.msi)? For the application? Is the icon to be treated as a file to be installed?