You can flick your fingers fast to scroll very quickly, and more comfortably than with a physical wheel.
I don't think the Magic Mice have simulated middle buttons – but the simulated scroll wheel on my Magic Mouse is better than any real scroll wheel I have ever used (except on a few overly-sensitive Web sites). Is this the middle mouse button? My old wireless mouse doesn't have this pressing the scroll wheel often scrolls instead of middle mouse buttoning.
Also, many of them have an extra button below the scroll wheel, e.g.
