3. Why are the system requirements so high?
The system requirements are actually super rough estimates I invented a long time ago, and maybe they should be updated. The reality is that you should be able to run the game on almost anything made in the last five years. You should especially note the game's video card requirement: "Intel Integrated Graphics." In other words, you can literally run this game on a laptop without a graphics card and expect a solid 60fps as long as you have a decent CPU (a 3ghz dual-core should be more than enough). If you only consider the game's memory footprint, I've never seen the game exceed 400mb. I rounded that tiny number up to 4gb and 8gb to account for the other requirements of a modern system, like the OS and other background apps.
So really, the reason for this inaccuracy is really just this: I don't have a QA department or leagues of testers. I came up with a rough estimate for what I thought you should need to have a good experience based on the devices I have at home. In terms of actual graphics requirements, I think the fact that the game doesn't require a video card is reasonably impressive. The game certainly runs much better than Minecraft without a dedicated video card.