I have found these are all possible
The plist file is easiest, there is a build setting info.plist
which must be updated accordingly.
For the icon and launch images, remove references from your project and then move the files on disc to some folder that makes sense for your codebase. Then add these items to the project (right-click, "add files to "). Finally, use a copy files build phase to copy them to the Resource folder, or possibly add them to a Copy Resource Bundle build phase.
When I did this, the files were copied into the App-Bundle itself, the iPad displayed them as expected, and XCode displayed the images in the Project Summary screen.