1. Of course you need the internet if you're hitting an api but the docs will get you to the point you can test it yourself without internet access by mocking their services.

2. If you're using a new framework or plugin you should have the source available in addition to the documentation. That should tell you all you need. 10 month "dusty" documentation means you're working with unstable code. If you don't have the source to inspect then you have other issues, the first being the proprietary code inflicted mess that you have to deal with.

3. You can download the stackoverflow databases of the topics you deem important and search through them.

My bet is that you haven't really even tried.