Hello, happy to answer your questions. There is a free member chat room on Patreon (it's quite new so I don't know if I set it up right), also my contact details are at the bottom of the Frequently Asked Questions section of the page.
1. That depends on the engine you are using. It is not possible for me to know how to import the assets for each and every different engine so you'll need to look it up :D Here's an example for unity.
2. That's the Royal Arena+ tileset. It is a Patreon exclusive asset. You get it with any of the pledge tiers.
3. As you've said, I draw what's chosen by the polls and that dictates what assets I publish month to month. I try my best to add futuristic options to the polls but the majority of the Patrons shy away from those options for some reason. I've drawn the Futuristic Labs Tileset as a bonus tileset by the way. It wasn't chosen by polls. I hoped it would maybe spark some interest in other futuristic assets but it didn't really work :) I might do more bonus stuff in the future but as of now, it seems the bulk of the assets are going to be fantasy based.
4. You get access to all assets through Patreon. No additional payments. You get links for every year, which is eight links. That gets you all the assets between 2018-2025. For 2026 you need to download the assets one by one, which is like three assets at the moment. The links will be in your welcome message and "membership" tab when you subscribe.
5. To be completely honest with you, I don't know :D Most of my time goes to doing the art and I am very lacking in gamedev matters. For mage arena I've imported the tilesets and rearranged them with the edit button within Unity "Tile Palette" and used them like that. I don't know if there is an easier way to import them in as they are seen in the tileset pngs themselves.
Thanks for you kind words! If you have any other questions feel free to reach out. You know how to contact me now :D