Some of what you are looking for is best requested via the Admin SDK. You may want to also check out other Google Data APIs in more detail, you could put together some good reporting tools.
Many of the APIs can be used in Google Apps Script by using the UrlFetch service. There's an OAuth flow built in that service that is quite nice for OAuth 1 flows, and it's not too bad to create a decent Google OAuth 2 flow with UrlFetch as well.
Then you can make authenticated requests to those APIs and handle the responses accordingly with Apps Script.