I have a US (Verizon) Galaxy S3 and my FiiO E18 works with it without needing any special app, It works with PowerAmp, Neutron, Spotify and Google's Music Player including streaming from Google's All Access subscription service. It works with Android Jelly Bean 4.3 and worked with the previous version of android as well.
You can certainly use it as a chain but if you want to use the DAC and Amp separately/independently you might not be able to. Something you should contact JDS about and word that very carefully. If you want to use it as a chain then you're in business as that's the common use.