Wrong on both counts.
Power brakes still work, they are just harder to push down to engage.
Also, no manufacturer is going to manufacture a car that would lock up the steering wheel if the key was turned off while it was engaged and rolling. Imagine the lawsuits as people said they accidently turned the key off or the engine started on fire OR as in these cases, the car overrevved.
Absolutely, completely the opposite of reality. Well, since 1970 or so. Try your own car and post details here if I'm wrong.
Most newer automatics won't even let you turn the key to the removal/lock wheel point if the car is in anything other than park or neutral - that is a built-in safety mechanism. Not sure how it works in some of these new cars where the start function is a button. I've seen some where you turn a key, and others where you simply insert it.