I want to experiment with in-app purchase, but before I can do that I need to create some products for the app in iTunes connect.
But I'm just experimenting and the app might never make it to the app store, is it possible to create a minimal placeholder app on iTunes connect (i.e. without having to add an app icon, screenshot, etc. etc. etc.) which can later be deleted?
You can do this but you might need to add some dummy images to make iTC happy. Just create some white squares of the needed size in your favorite paint program. Use those where you must upload an icon or screen shot.
Make sure you give the app a name you will never ever actually want to use. Once you delete an app, you can never use that title again. So enter some random gibberish for the name.
Yes, but you must add an app icon and stuff... but thats easy, upload any 1024x1024 image for the app icon and any screenshot. When your're done delete the app from iTC.
Also: Make SURE you will Never use the app name again.