I think Personal Documents currently only works with Kindle E Ink models and the Kindle for PC/Mac apps. It does not yet work for Android and iOS apps. The Fire has not yet reached anyone, so we don't know if it works on it yet.

I think syncing of farthest page read, highlighting, notes, etc. should work on all the apps for which it is enabled for books you can archive, that is directly bought from Amazon and unmodified.