You can but very few people drive stick in the US and, of those, I suspect very few use engine breaking for a significant fraction of their braking. For getting off a highway maybe, but probably not for stop and go in a city.
This is not true. There are specific areas that ban it and have signage alerting drivers to that fact, but it is not common.
Plus, it typically only applies to Semis as their engine braking is especially noisy. On a typical gas powered sedan you would be hard pressed to identify that someone is engine braking unless you were right next to it. Being prosecuted for it would be even more exceptional.