1) He will be able to access FM GO, but not use it to access files hosted on the server. Local files on the device, that can be set up to synch data with the hosted files would be accessible.
2) this is not a built in feature of FM GO. Several third part developers such as SeedCode and 360Works offer a Synch tool that you can use to do the synchronizing.
FileMaker also has a reference document on Synching data: http://www.filemaker.com/solutions/ios/docs/fmi_guide_sync_en.pdf