It has charging management circuitry but that doesn't prevent it from over-cycling if someone just leaves it plugged in all the time. All it does is bounce the charge from 98% to 100% repeatedly. Show me a single example of a piece of electronics that has "solved" this problem...
No idea. I just know what the Apple engineer on HN said about the Magic Mouse 2 when it was released. I would imagine that the keyboard battery might be larger and, therefore, may be able to withstand more charge/discharge cycles but that's just speculation on my part.
