Hello,
I'm a Canadian software engineer who's been working with Android since the beginning.
You don't mention whether you have other Android software that does something with the files retrieved. That obviously could change the design so it would be something I need to know.
It would be fairly easy to write an FTP client, and run it in an Android service
There are a lot of details I would need to know, so please send a message if you want to discuss it.
Cheers,
R. Brad Gies