Will I be able to download and start another exe-file using my click once deployment? I already have the functionality that downloads and updates my application files, so I would really like for a Click Once installer to just download my existing launcher, create a shortcut for it and then start the launcher and have my current functionality work as before.
I think this is similar to how Google Chrome does it?
Yes, it is possible for ClickOnce to deploy multiple exe files. The only stipulation is that one exe must be designated as the "Entry Point" exe. The entry point exe must be a .Net executable.
One thing to note about this approach - you don't want your users to ever launch your app directly. If users launch the application directly and not through the entry point exe, you will lose the nice self-update features ClickOnce provides.