Yes, a little practice might help, but it's not exactly the most difficult skill. I rarely emergency brake because good cycle craft expects us to be aware of other traffic and their likely behaviour. Thus most of the incidents on my video I've only needed to slow down gradually, with the exception of the nearly over the bonnet clip.
The times I do need to emergency brake are mostly due to me being impatient and in a hurry, and not allowing enough of a safety zone. Still get the airzound on though.
I can't see your example with hooting in the car - I don't have a problem with that either. Oh, and I probably wouldn't hoot after braking, because the reason for hooting has gone by then and you're not supposed to hoot in retribution.