When an apk gets uploaded it generates a link for the app to the play store. I want to distribute the link and the QR code in a printable paper. If I upload a new version of the apk, does the link change and render the previous printed paper useless?
Link to application in Google Play is created from package name of your *.apk file and it never changes after update. Moreover you should never change your package name. When you use link like this:
You can be sure that it will be permanent. You can read also very old article about things that cannot change in android application.