No, just install the updated APK without uninstalling the previous version, and it will update and keep your save file. Also, you should be able to link to Facebook, but I had to disable the Facebook app first before linking my save file.
Hello! I have a question. If I activate "Gem & Coin consume 0" my gem and coin counter go to 0. If I activate it, buy things and then desactivate it, will I get back my gems and coins or i'll have 0 until i get more?