A person in the U.S., be they citizen or foreigner, are subject to the jurisdiction of the U.S. If they rob a bank, kill an person, or commit any other crime then they can, and will, be arrested, tried, and jailed. The exception are people like the ambassador's wife you mentioned who enjoy diplomatic or any other form of immunity that prevents them from being held accountable to our laws.
Not so. They cannot be drafted into military service etc. They do not have ANY of the responsibilities of a citizen. They are in the country but not part of the country.
Exactly the same as consulate personnel. they are not subject to the jurisdiction of the US.