I wouldn’t use true projectiles for pistols and rifles, I’d use them for weapons such as rocket launcher though. This way the performance impact shouldn’t be too great.
The updates are free and they become available for download automatically.
You can save the world data to MySQL database in the same way the character data is saved now. You would have to create a new php script similar to savecharacter.php, and handle sending the request in JSONRequests blueprint. In MMOGame or some other server blueprint you can set use a Set Timer Delegate node that will call the request every 5 mins or so.
I plan to change XYZButton to InputAction soon but the rest of MyCharacter etc blueprints will mostly stay the same.