I don't think that CRM Online is included with Action Pack or MSDN. That being said, you do get the on-premise license with MSDN, so you can install it locally and test your integration.
The Online and On-Premise editions are identical, save for how you actually authenticate to access the web services. Online will use Office365 integration authentication.
You can get a 30-day trial subscription to CRM Online, so if you get your integration to a point where you are ready to test it, you can get that trial and work out any issues within the trial timeframe.
Good luck!