Seems like they use JavaScript and this might qualify for the HTML5/JavaScript exception that Apple has. Also it seems like they are a lot less powerful than Roblox scripts, and there isn't an in-game store allowing you to purchase them without using Apple's in-app purchase flow.
Yup! Soft currency (Minecoins) travel with you with your Microsoft account and can be used on what ever device you sign into (including iOS). You can also purchase more Minecoins in the game its self each platform.