It is 100% attention. The caveat is there is ample time after the car notifies you to take control where you put down your task, look around and gain situational awareness. How often that happens is a question. Seemingly rare enough you could reliably do a meeting, that latter part is just a presumption though.

No '*', Mercedes takes full responsibility and there are many seconds before it shifts control (and liability). The system can reliably predict when it will want to give back control.