I purchased the game and it won't download or install correctly
Downloads and installations occasionally glitch or stall out, try waiting a little bit restarting the device and re-downloading it. You don't get charged twice if you've already purchased it. If it still doesn't work, apple support may be able to resolve the issue.
I bought the game and don't like it or it's not what I expected, I can't figure it out or I have some unresolvable issue with it
You can hit up apple support and request a refund. Apple handles support for all app store download/and payment related issues
I changed device/cleared my application data/or something happened and I can't find my world, help!
The only way to recover worlds is if they were backed up on iCloud, or through the in game sharing system. Backup your worlds regularly to avoid losing your builds!
I wandered away from my buildings and now I can't find them
Open the build menu and press the house button, to warp back to the location you spawned. Set your home location to where your buildings are to make sure you can always find them.
This is a starting draft, more to come...