Hi Niniann,
Thank you for your feedback!
1. To allow the player to customize keybindings, you probably want to look for a plugin that enables you to bind keys and to call Common Events or custom scripting, and then you could look at the public functions offered by the minimap from here: Minimap – Aerosys' Blog
2. Your procedure looks good so far. Right now, only a few people (or maybe even none at all) are using GALVLayerSupport, so it may be possible that my code has some errors in it. Please try it again with all other plugins deactivated besides GALV and Minimaps? (Yes, also deactivate any other MK plugin, too)
3. The same as for #2, please disable any other plugin and let me know whether that affects the minimap. I also would like to know whether your game's FPS stays at 60 or whether there is any bottleneck (either in mine or any other creator's plugins) - You can display the FPS by pressing F2 when running the game.