Thanks for posting.
Your assumptions are correct: FileMaker Pro or Server would host a .fp7 database. You would create a real time connection between the .fp7 database and an external SQL source (Microsoft SQL Server 2008 is supported) through FileMaker's ESS feature. FileMaker Go would connect to the database and have access to the external SQL source just as any FileMaker Pro client would have.
To get a better idea of how FileMaker interacts with external SQL sources, it may be beneficial to download and try our fully featured 30 day trial of FileMaker Pro here:
For more information, here is the external SQL data sources page from the FileMaker website:
And here is a technical brief on the introduction to ESS:
Hope this helps,