1: Yes, works with macbook's built-in Bluetooth receiver. Do not need to plug anything in.
2: Batteries will last years before needing to be replaced
3. not really a fan of the round keys (both aesthetically and functionally) I sometimes feel like I'm missing keys slightly due to their shape and the slightly tighter spacing than a standard size keyboard. Typing is nice and quiet, with good travel. Keys have a springiness to them, up to you to decide if you like that feeling.