I have created a tool for importing schematic files into MCPE worlds directly from Android. With the tool you can Import hundreds of schematics from online sources including houses, castles , fortresses, etc with just a few taps. Additionally you can edit a whole bunch of stuff (Health, span mobs, edit inventory, edit chests, and much more).
I've put a lot of effort into this tool and I hope you enjoy it. I'd love to hear feedback to continuously improve it.
Schematic Import (also a free version) is on the Play Store.