Will "deleting" an icon from the home-screen only delete the icon, or also uninstall the app?
Deleting an icon usually only removes the icon, not the app itself. However, if your launcher's home screen is merged with app drawer of the launcher, then it is likely it would delete the app. In the former case, launchers know that it is just the icon that is to be removed, so no user approval in the form of dialog is required.

I suggest you try to find it out on your own what actually would happen. Install a fairly harmless app, such as this one, and try to remove its icon. You would have your answer right away.