I agree, it is confusing.
And not always easy to get information on.
I have noticed some of the articles on the Scirra site have been updated, (as they mention things like iOS 8 in an article dated 2012) but it would be nice if the dates were updated along with the article so you can be sure the information is current and you're not wasting time. I'd rather know how current the information is rather then when the article was originally posted. Things change quickly in programing.
I can't help you much, but in my searches for an answer to "in app purchases" I found the Metro plugin worked the best. At least in the last game I made.
Your question about IAP and windows 8. I believe they are two different systems that do similar things. So it's either or. I haven't gotten either of them to work in test mode in VS13 (4).
IAP plugin would be better if you were writing for multiple platforms.
The article below is from the guy that wrote the Metro Plugin. Which is probably as good a template as any for the order of doing things since Metro was based on the Windows 8 plugin, I believe.
c2metro.wordpress.com/2012/10/0 ... -revisted/
If you're doing a remove ads you could just go old school like I did and publish two versions of you app. One named "yourAppName" and one named "yourAppName Free"(this one has the ads of course). I use the same capx file. I just wrote a function to destroy all ad related objects, which I call from onStart, and comment out for the paid or ad free version.
I would include the windows 8 plugin though. You don't have to use it and it makes you the correct and pertinent charms bar web pages like privacy.html and about to get acceptance from the windows store. I think the windows export module is suppose to make these pages, but I don't think it does.
You can check out my game here. apps.microsoft.com/windows/app/p ... a6e6431f88
It just went live yesterday.
I don't think we should be posting here as this is off topic for this forum but I wanted to send you something. It's always good to know you're being heard.