Happy to know that you found the post very lucid. I hope the following points help you with your queries:
1. In-app purchases would refer to revenue that flows through the app stores. It would not include other revenue generators like the official website, for example.
2. The data pertaining to Southeast Asia does not include India, primarily because the regional trends vary. Coming to your other point, we did analyse region specific trends for video app downloads and spending, but it did reveal much other than what the broad data already says, which is why we did not include it in our data visualisation.