Where did you find about android:debuggable and why do you need to change it?
.
Cocoon and Intel XDK are gone, they don't work anymore, don't use them.
Now you have two main options - use the official IAP plugin, or use Enhance plugin.
I don't know if there are any good tutorials for IAP plugin, you can search the forum. For example, see screenshot in this post, it's for C3, but should be quite similar:
construct.net/en/forum/construct-3/how-do-i-8/mobile-iap-133253
.
Enhance may be easier to use and it has a demo project included with the plugin.