question

First, you should never update to a new version of a file in Content without changing the filename - have a version number as part of the name itself. The reason for this is that the cache time on a CDN like CloudFront (which we use for Content) is very long. So if you just use the same filename, it can take quite a while before all the various distribution nodes have the updated file. A new filename will guarantee that the new file is cached at all endpoints as it is requested.

Now, for querying the file from the device, the best thing to do is store a "manifest" containing the information on the latest revision of your content files in Title Data. That way, you can grab it on start of the game, and check to see if you need to update anything.