I'm not sure on the maps/items. Hundreds of each, haha.
No, I have programmed/redesigned a lot of systems in the engine myself to get the game to where it is now, especially so the item upgrading, the character menu, challenges, dungeons, etc.
Though the skilling system is just event based. All there is to it is a currency that resources always drop that is essentially your EXP, and permits you can buy that are just events that raise a player variable by 1. You can easily check on that player variable to see if the player can interact with some resource.