Hi,
The opt-in is only for "open" beta testing
you will get a link like this one for example :
https://play.google.com/apps/testing/com.jinxter.HitTheLightthen you can share that link on FB for example.
I never tried the example files.
in the game i linked i simply use :
"AN_initBilling" at the start of the game.
then after some ads are shown i have a popup with 2 buttons, when no ads forever is pressed it will trigger "AN_Purchase"
I also use "AN_ISProductPurchased" to check if the product is purchased (right after initBilling)
If you want to show the price on your buy screen you can use "AN_RetriveProductInfo" to get all the info on that product, then use a set text/string to display it.
Also what i noticed on the top/left from the 2nd picture that is says draft, it must be published.
and there must be some reason that you can't publish, you can try clicking "Why Can't I Publish?"
Maybe you app does not have a 'keystore' yet.